US9214150B2 - Continuous adaptation of secondary path adaptive response in noise-canceling personal audio devices - Google Patents

Continuous adaptation of secondary path adaptive response in noise-canceling personal audio devices Download PDF

Info

Publication number
US9214150B2
US9214150B2 US13/458,585 US201213458585A US9214150B2 US 9214150 B2 US9214150 B2 US 9214150B2 US 201213458585 A US201213458585 A US 201213458585A US 9214150 B2 US9214150 B2 US 9214150B2
Authority
US
United States
Prior art keywords
signal
amplitude
audio
noise
source
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active, expires
Application number
US13/458,585
Other versions
US20120308027A1 (en
Inventor
Nitin Kwatra
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cirrus Logic Inc
Original Assignee
Cirrus Logic Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to US201161493162P priority Critical
Application filed by Cirrus Logic Inc filed Critical Cirrus Logic Inc
Priority to US13/458,585 priority patent/US9214150B2/en
Assigned to CIRRUS LOGIC, INC. reassignment CIRRUS LOGIC, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KWATRA, NITIN
Publication of US20120308027A1 publication Critical patent/US20120308027A1/en
Application granted granted Critical
Publication of US9214150B2 publication Critical patent/US9214150B2/en
Application status is Active legal-status Critical
Adjusted expiration legal-status Critical

Links

Images

Classifications

    • G10K11/1784—
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1781—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions
    • G10K11/17813—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms
    • G10K11/17817—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms between the output signals and the error signals, i.e. secondary path
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/108—Communication systems, e.g. where useful sound is kept and noise is cancelled
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3049—Random noise used, e.g. in model identification

Abstract

A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone is also provided proximate the speaker to provide an error signal indicative of the effectiveness of the noise cancellation. A secondary path estimating adaptive filter is used to estimate the electro-acoustical path from the noise canceling circuit through the transducer so that source audio can be removed from the error signal. Noise is injected either continuously and inaudibly below the source audio, or in response to detection that the source audio is low in amplitude, so that the adaptation of the secondary path estimating adaptive filter can be maintained, irrespective of the presence and amplitude of the source audio.

Description

This U.S. Patent Application Claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application Ser. No. 61/493,162 filed on Jun. 3, 2011.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to personal audio devices such as wireless telephones that include adaptive noise cancellation (ANC), and more specifically, to control of ANC in a personal audio device that uses injected noise to provide continued adaptation of a secondary path estimate when source audio is absent or low in amplitude.

2. Background of the Invention

Wireless telephones, such as mobile/cellular telephones, cordless telephones, and other consumer audio devices, such as mp3 players, are in widespread use. Performance of such devices with respect to intelligibility can be improved by providing noise canceling using a microphone to measure ambient acoustic events and then using signal processing to insert an anti-noise signal into the output of the device to cancel the ambient acoustic events.

Noise canceling operation can be improved by measuring the transducer output of a device at the transducer to determine the effectiveness of the noise canceling using an error microphone. The measured output of the transducer is ideally the source audio, e.g., downlink audio in a telephone and/or playback audio in either a dedicated audio player or a telephone, since the noise canceling signal(s) are ideally canceled by the ambient noise at the location of the transducer. To remove the source audio from the error microphone signal, the secondary path from the transducer through the error microphone can be estimated and used to filter the source audio to the correct phase and amplitude for subtraction from the error microphone signal. However, when source audio is absent, the secondary path estimate cannot typically be updated.

Therefore, it would be desirable to provide a personal audio device, including wireless telephones, that provides noise cancellation using a secondary path estimate to measure the output of the transducer and that can continuously adapt the secondary path estimate independent of whether source audio of sufficient amplitude is present.

SUMMARY OF THE INVENTION

The above stated objective of providing a personal audio device providing noise cancelling including a secondary path estimate that can be adapted continuously whether or not source audio of sufficient amplitude is present, is accomplished in a personal audio device, a method of operation, and an integrated circuit.

The personal audio device includes a housing, with a transducer mounted on the housing for reproducing an audio signal that includes both source audio for providing to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer. A reference microphone is mounted on the housing to provide a reference microphone signal indicative of the ambient audio sounds. The personal audio device further includes an adaptive noise-canceling (ANC) processing circuit within the housing for adaptively generating an anti-noise signal from the reference microphone signal such that the anti-noise signal causes substantial cancellation of the ambient audio sounds. An error microphone is included for controlling the adaptation of the anti-noise signal to cancel the ambient audio sounds and for correcting for the electro-acoustical path from the output of the processing circuit through the transducer. The ANC processing circuit injects noise at a level sufficiently below the source audio level to be unnoticeable, either continuously, or at least when the source audio, e.g., downlink audio in telephones and/or playback audio in media players or telephones, is at such a low level that the secondary path estimating adaptive filter cannot properly continue adaptation.

The foregoing and other objectives, features, and advantages of the invention will be apparent from the following, more particular, description of the preferred embodiment of the invention, as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a wireless telephone 10 in accordance with an embodiment of the present invention.

FIG. 2 is a block diagram of circuits within wireless telephone 10 in accordance with an embodiment of the present invention.

FIG. 3 is a block diagram depicting signal processing circuits and functional blocks within ANC circuit 30 of CODEC integrated circuit 20 of FIG. 2 in accordance with an embodiment of the present invention.

FIG. 4 is a block diagram depicting signal processing circuits and functional blocks within an integrated circuit in accordance with an embodiment of the present invention.

 DESCRIPTION OF ILLUSTRATIVE EMBODIMENT

The present invention encompasses noise canceling techniques and circuits that can be implemented in a personal audio device, such as a wireless telephone. The personal audio device includes an adaptive noise canceling (ANC) circuit that measures the ambient acoustic environment and generates a signal that is injected into the speaker (or other transducer) output to cancel ambient acoustic events. A reference microphone is provided to measure the ambient acoustic environment, and an error microphone is included to measure the ambient audio and transducer output at the transducer, thus giving an indication of the effectiveness of the noise cancelation. A secondary path estimating adaptive filter is used to remove the playback audio from the error microphone signal, in order to generate an error signal. However, depending on the presence (and level) of the audio signal reproduced by the personal audio device, e.g., downlink audio during a telephone conversation or playback audio from a media file/connection, the secondary path adaptive filter may not be able to continue to adapt to estimate the secondary path. Therefore, the present invention uses injected noise to provide enough energy for the secondary path estimating adaptive filter to continue to adapt, while remaining at a level that is unnoticeable to the listener.

Referring now to FIG. 1, a wireless telephone 10 is illustrated in accordance with an embodiment of the present invention is shown in proximity to a human ear 5. Illustrated wireless telephone 10 is an example of a device in which techniques in accordance with embodiments of the invention may be employed, but it is understood that not all of the elements or configurations embodied in illustrated wireless telephone 10, or in the circuits depicted in subsequent illustrations, are required in order to practice the invention recited in the Claims. Wireless telephone 10 includes a transducer such as speaker SPKR that reproduces distant speech received by wireless telephone 10, along with other local audio event such as ringtones, stored audio program material, injection of near-end speech (i.e., the speech of the user of wireless telephone 10) to provide a balanced conversational perception, and other audio that requires reproduction by wireless telephone 10, such as sources from web-pages or other network communications received by wireless telephone 10 and audio indications such as battery low and other system event notifications. A near-speech microphone NS is provided to capture near-end speech, which is transmitted from wireless telephone 10 to the other conversation participant(s).

Wireless telephone 10 includes adaptive noise canceling (ANC) circuits and features that inject an anti-noise signal into speaker SPKR to improve intelligibility of the distant speech and other audio reproduced by speaker SPKR. A reference microphone R is provided for measuring the ambient acoustic environment and is positioned away from the typical position of a user's mouth, so that the near-end speech is minimized in the signal produced by reference microphone R. A third microphone, error microphone E, is provided in order to further improve the ANC operation by providing a measure of the ambient audio combined with the audio reproduced by speaker SPKR close to ear 5, when wireless telephone 10 is in close proximity to ear 5. Exemplary circuit 14 within wireless telephone 10 includes an audio CODEC integrated circuit 20 that receives the signals from reference microphone R, near speech microphone NS, and error microphone E and interfaces with other integrated circuits such as an RF integrated circuit 12 containing the wireless telephone transceiver. In other embodiments of the invention, the circuits and techniques disclosed herein may be incorporated in a single integrated circuit that contains control circuits and other functionality for implementing the entirety of the personal audio device, such as an MP3 player-on-a-chip integrated circuit.

In general, the ANC techniques of the present invention measure ambient acoustic events (as opposed to the output of speaker SPKR and/or the near-end speech) impinging on reference microphone R, and by also measuring the same ambient acoustic events impinging on error microphone E, the ANC processing circuits of illustrated wireless telephone 10 adapt an anti-noise signal generated from the output of reference microphone R to have a characteristic that minimizes the amplitude of the ambient acoustic events present at error microphone E. Since acoustic path P(z) extends from reference microphone R to error microphone E, the ANC circuits are essentially estimating acoustic path P(z) combined with removing effects of an electro-acoustic path S(z). Electro-acoustic path S(z) represents the response of the audio output circuits of CODEC IC 20 and the acoustic/electric transfer function of speaker SPKR including the coupling between speaker SPKR and error microphone E in the particular acoustic environment. S(z) is affected by the proximity and structure of ear 5 and other physical objects and human head structures that may be in proximity to wireless telephone 10, when wireless telephone is not firmly pressed to ear 5. While the illustrated wireless telephone 10 includes a two microphone ANC system with a third near speech microphone NS, some aspects of the present invention may be practiced in a system in accordance with other embodiments of the invention that do not include separate error and reference microphones, or yet other embodiments of the invention in which a wireless telephone uses near speech microphone NS to perform the function of the reference microphone R. Also, in personal audio devices designed only for audio playback, near speech microphone NS will generally not be included, and the near-speech signal paths in the circuits described in further detail below can be omitted, without changing the scope of the invention.

Referring now to FIG. 2, circuits within wireless telephone 10 are shown in a block diagram. CODEC integrated circuit 20 includes an analog-to-digital converter (ADC) 21A for receiving the reference microphone signal and generating a digital representation ref of the reference microphone signal, an ADC 21B for receiving the error microphone signal and generating a digital representation err of the error microphone signal, and an ADC 21C for receiving the near speech microphone signal and generating a digital representation ns of the error microphone signal. CODEC IC 20 generates an output for driving speaker SPKR from an amplifier A1, which amplifies the output of a digital-to-analog converter (DAC) 23 that receives the output of a combiner 26. Combiner 26 combines audio signals ia from internal audio sources 24, the anti-noise signal anti-noise generated by ANC circuit 30, which by convention has the same polarity as the noise in reference microphone signal ref and is therefore subtracted by combiner 26, a portion of near speech signal ns so that the user of wireless telephone 10 hears their own voice in proper relation to downlink speech ds, which is received from radio frequency (RF) integrated circuit 22. In accordance with an embodiment of the present invention, downlink speech ds is provided to ANC circuit 30, which, when both downlink speech ds and internal audio ia are absent or low in amplitude, adds noise to the combined source audio signal including downlink speech ds and internal audio ia or replaces source audio (ds+ia) with an injected noise signal. The downlink speech ds, internal audio ia, and noise (or source audio/noise if applied as alternative signals) are provided to combiner 26, so that signal (ds+ia+noise) is always present to estimate acoustic path P(z) with a secondary path adaptive filter within ANC circuit 30. Near speech signal ns is also provided to RF integrated circuit 22 and is transmitted as uplink speech to the service provider via antenna ANT.

Referring now to FIG. 3, details of ANC circuit 30 are shown in accordance with an embodiment of the present invention. An adaptive filter 32 receives reference microphone signal ref and under ideal circumstances, adapts its transfer function W(z) to be P(z)/S(z) to generate the anti-noise signal anti-noise, which is provided to an output combiner that combines the anti-noise signal with the audio to be reproduced by the transducer, as exemplified by combiner 26 of FIG. 2. The coefficients of adaptive filter 32 are controlled by a W coefficient control block 31 that uses a correlation of two signals to determine the response of adaptive filter 32, which generally minimizes the error, in a least-mean squares sense, between those components of reference microphone signal ref present in error microphone signal err. The signals processed by W coefficient control block 31 are the reference microphone signal ref as shaped by a copy of an estimate of the response of path S(z) provided by filter 34B and another signal that includes error microphone signal err. By transforming reference microphone signal ref with a copy of the estimate of the response of path S(z), response SECOPY(z), and minimizing error microphone signal err after removing components of error microphone signal err due to playback of source audio, adaptive filter 32 adapts to the desired response of P(z)/S(z). In addition to error microphone signal err, the other signal processed along with the output of filter 34B by W coefficient control block 31 includes an inverted amount of the source audio including downlink audio signal ds and internal audio ia that has been processed by filter response SE(z), of which response SECOPY(z) is a copy. By injecting an inverted amount of source audio, adaptive filter 32 is prevented from adapting to the relatively large amount of source audio present in error microphone signal err and by transforming the inverted copy of downlink audio signal ds and internal audio ia with the estimate of the response of path S(z), the source audio that is removed from error microphone signal err before processing should match the expected version of downlink audio signal ds, and internal audio ia reproduced at error microphone signal err, since the electrical and acoustical path of S(z) is the path taken by downlink audio signal ds and internal audio ia to arrive at error microphone E. Filter 34B is not an adaptive filter, per se, but has an adjustable response that is tuned to match the response of adaptive filter 34A, so that the response of filter 34B tracks the adapting of adaptive filter 34A.

To implement the above, adaptive filter 34A has coefficients controlled by SE coefficient control block 33, which processes the source audio (ds+ia) and error microphone signal err after removal, by a combiner 36, of the above-described filtered downlink audio signal ds and internal audio ia, that has been filtered by adaptive filter 34A to represent the expected source audio delivered to error microphone E. Adaptive filter 34A is thereby adapted to generate a signal from downlink audio signal ds and internal audio ia, that when subtracted from error microphone signal err, contains the content of error microphone signal err that is not due to source audio (ds+ia). However, if downlink audio signal ds and internal audio ia are both absent, or have very low amplitude, SE coefficient control block 33 will not have sufficient input to estimate acoustic path S(z). Therefore, in ANC circuit 30, a source audio detector 35, which detects whether sufficient source audio (ds+ia) is present, and updates the secondary path estimate if sufficient source audio (ds+ia) is present. Source audio detector 35 may be replaced by a speech presence signal if such is available from a digital source of the downlink audio signal ds, or a playback active signal provided from media playback control circuits. A selector 38 selects the output of a noise generator 37 if source audio (ds+ia) is absent or low in amplitude, which provides output ds+ia/noise to combiner 26 of FIG. 2, and an input to secondary path adaptive filter 34A and SE coefficient control block 33, allowing ANC circuit 30 to maintain estimating acoustic path S(z). Alternatively, selector 38 can be replaced with a combiner that adds the noise signal to source audio (ds+ia).

When source audio (ds+ia) is absent, speaker SPKR of FIG. 1 will actually reproduce noise injected from noise generator 37, thus it would be undesirable for the user of the device to hear the injected noise. Therefore, ANC circuit 30 includes a signal level comparator 39 that compares the output of secondary path adaptive filter 34A with error microphone signal err. The output of secondary path adaptive filter 34A provides a good estimate of the downlink speech ds or injected noise that the user actually hears, since acoustic path S(z) that is estimated by secondary path adaptive filter 34A is the path from the speaker SPKR to error microphone E. Error microphone signal err is then used to determine a comparison threshold, since error microphone signal err is a measure of the total energy heard by the user. As an alternative, predetermined or other dynamic thresholds may be used, such as thresholds determined from the reference microphone signal ref or near speech signal ns. A criteria such as maintaining the level of the output of secondary path adaptive filter 34A at 20 dB below the corresponding normalized level of error microphone signal err can be used to either adjust the gain of the output of noise generator 37 using gain control A2, or to further condition the selection of the output of noise generator 37 by selector 38 so that noise injection is stopped when the amplitude of the output of secondary path adaptive filter 34A becomes too great relative to error microphone signal err. The amplitude of the output of secondary path adaptive filter 34A and error microphone signal err can be determined by techniques such as least-mean-squares, squarers, absolute value peak detectors or decimators. The following control equation can be used to adjust the gain applied to the injected noise:
gain(i)=gain(i−1)+(mag(err)/atten−mag(seout))
where i is the step interval, atten is the desired ratio of the amplitude of the error signal to the noise (desired attenuation, e.g., 20 dB), ampl(err) is the magnitude of the error signal and mag(seout) is the magnitude of the output of the secondary path adaptive filter 34A.

Referring now to FIG. 4, a block diagram of an ANC system is shown for illustrating ANC techniques in accordance with an embodiment of the invention, as may be implemented within CODEC integrated circuit 20. Reference microphone signal ref is generated by a delta-sigma ADC 41A that operates at 64 times oversampling and the output of which is decimated by a factor of two by a decimator 42A to yield a 32 times oversampled signal. A delta-sigma shaper 43A spreads the energy of images outside of bands in which a resultant response of a parallel pair of filter stages 44A and 44B will have significant response. Filter stage 44B has a fixed response WFIXED(z) that is generally predetermined to provide a starting point at the estimate of P(z)/S(z) for the particular design of wireless telephone 10 for a typical user. An adaptive portion WADAPT(z) of the response of the estimate of P(z)/S(z) is provided by adaptive filter stage 44A, which is controlled by a leaky least-means-squared (LMS) coefficient controller 54A. Leaky LMS coefficient controller MA is leaky in that the response normalizes to flat or otherwise predetermined response over time when no error input is provided to cause leaky LMS coefficient controller 54A to adapt. Providing a leaky controller prevents long-term instabilities that might arise under certain environmental conditions, and in general makes the system more robust against particular sensitivities of the ANC response.

In the system depicted in FIG. 4, the reference microphone signal is filtered by a copy SECOPY(z) of the estimate of the response of path S(z), by a filter 51 that has a response SECOPY(z), the output of which is decimated by a factor of 32 by a decimator 52A to yield a baseband audio signal that is provided, through an infinite impulse response (IIR) filter 53A to leaky LMS 54A. Filter 51 is not an adaptive filter, per se, but has an adjustable response that is tuned to match the combined response of filter stages 55A and 55B, so that the response of filter 51 tracks the adapting of response SE(z). The error microphone signal err is generated by a delta-sigma ADC 41C that operates at 64 times oversampling and the output of which is decimated by a factor of two by a decimator 42B to yield a 32 times oversampled signal. As in the system of FIG. 3, an amount of source audio (ds+ia) that has been filtered by an adaptive filter to apply response S(z) is removed from error microphone signal err by a combiner 46C, the output of which is decimated by a factor of 32 by a decimator 52C to yield a baseband audio signal that is provided, through an infinite impulse response (IIR) filter 53B to leaky LMS 54A. Response S(z) is produced by another parallel set of filter stages 55A and 55B, one of which, filter stage 55B has fixed response SEFIXED(z), and the other of which, filter stage 55A has an adaptive response SEADAPT(z) controlled by leaky LMS coefficient controller MB. The outputs of filter stages 55A and 55B are combined by a combiner 46E. Similar to the implementation of filter response W(z) described above, response SEFIXED(z) is generally a predetermined response known to provide a suitable starting point under various operating conditions for electrical/acoustical path S(z). Filter 51 is a copy of adaptive filter 55A/55B, but is not itself an adaptive filter, i.e., filter 51 does not separately adapt in response to its own output, and filter 51 can be implemented using a single stage or a dual stage. A separate control value is provided in the system of FIG. 4 to control the response of filter 51, which is shown as a single adaptive filter stage. However, filter 51 could alternatively be implemented using two parallel stages and the same control value used to control adaptive filter stage 55A could then be used to control the adjustable filter portion in the implementation of filter 51.

As in ANC circuit 30 of FIG. 3, the input to filter stages 55A and 55B has a component selected from source audio (ds+ia) or the output of noise generator 37 with gain controlled by gain control A2, as selected by selector 38, the output of which is provided to the input of a combiner 46D that adds a portion of near-end microphone signal ns that has been generated by sigma-delta ADC 41B and filtered by a sidetone attenuator 56 to prevent feedback conditions. The output of combiner 46D is shaped by a sigma-delta shaper 43B that provides inputs to filter stages 55A and 55B that has been shaped to shift images outside of bands where filter stages 55A and 55B will have significant response. Signal level comparator 39 compares the output of combiner 46E, which is the output of the secondary path adaptive filter formed by filter stages 55A and 55B, and error microphone signal err and controls the gain applied to the output of noise generator 37 via gain control A2 in conformity with a result of the comparison. Speech detector 35 controls whether selector selects source audio (ds+ia) or the output of gain control A2 as in ANC circuit 30 of FIG. 3. The inputs to leaky LMS control block 54B are also at baseband, provided by decimating a combination of the selected source audio/noise, provided by selector 38, by a decimator 52B that decimates by a factor of 32, and another input is provided by decimating the output of a combiner 46C that has removed the signal generated from the combined outputs of adaptive filter stage 55A and filter stage 55B that are combined by another combiner 46E from error microphone signal err. As mentioned above, selector 38 can alternatively be replaced by a combiner that combines the noise signal with source audio (ds+ia). The output of combiner 46C represents error microphone signal err with the components due to source audio (ds+ia) removed, which is provided to LMS control block 54B after decimation by decimator 52C. The other input to LMS control block 54B is the baseband signal produced by decimator 52B. The above arrangement of baseband and oversampled signaling provides for simplified control and reduced power consumed in the adaptive control blocks, such as leaky LMS controllers MA and 54B, while providing the tap flexibility afforded by implementing adaptive filter stages 44A-44B, 55A-55B and filter 51 at the oversampled rates.

In accordance with an embodiment of the invention, the output of combiner 46D is also combined with the output of adaptive filter stages 44A-44B that have been processed by a control chain that includes a corresponding hard mute block 45A, 45B for each of the filter stages, a combiner 46A that combines the outputs of hard mute blocks 45A, 45B, a soft mute 47 and then a soft limiter 48 to produce the anti-noise signal that is subtracted by a combiner 46B with the source audio output of combiner 46D. The output of combiner 46B is interpolated up by a factor of two by an interpolator 49 and then reproduced by a sigma-delta DAC 50 operated at the 64 x oversampling rate. The output of DAC 50 is provided to amplifier A1, which generates the signal delivered to speaker SPKR.

Each or some of the elements in the system of FIG. 4, as well in as the exemplary circuits of FIG. 2 and FIG. 3, can be implemented directly in logic, or by a processor such as a digital signal processing (DSP) core executing program instructions that perform operations such as the adaptive filtering and LMS coefficient computations. While the DAC and ADC stages are generally implemented with dedicated mixed-signal circuits, the architecture of the ANC system of the present invention will generally lend itself to a hybrid approach in which logic may be, for example, used in the highly oversampled sections of the design, while program code or microcode-driven processing elements are chosen for the more complex, but lower rate operations such as computing the taps for the adaptive filters and/or responding to detected changes in ear pressure as described herein.

While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form, and details may be made therein without departing from the spirit and scope of the invention.

Claims (24)

What is claimed is:
1. A personal audio device, comprising:
a personal audio device housing;
a transducer mounted on the housing for reproducing an audio signal including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer;
a first combiner for combining a source audio signal containing the source audio and the anti-noise signal to provide an output signal for reproduction by the transducer;
a reference microphone mounted on the housing for providing a reference microphone signal indicative of the ambient audio sounds;
an error microphone mounted on the housing in proximity to the transducer for providing an error microphone signal indicative of the acoustic output of the transducer and the ambient audio sounds at the transducer;
a controllable noise source for providing a noise signal;
a source audio detector having an input coupled to the source audio signal for determining whether source audio of sufficient amplitude is present in the source audio signal; and
a processing circuit that generates the anti-noise signal from the reference microphone signal to reduce the presence of the ambient audio sounds heard by the listener in conformity with an error signal and the reference microphone signal, wherein the processing circuit implements a secondary path adaptive filter having a secondary path response that shapes the source audio to generate shaped source audio and a second combiner that removes the shaped source audio from the error microphone signal to provide the error signal, and wherein the processing circuit, in response to the source audio detector determining that source audio of sufficient amplitude is not present in the source audio signal, selectively injects noise from the controllable noise source into the secondary path adaptive filter and further injects the noise into the first combiner in place of or in combination with the source audio signal to cause the secondary path adaptive filter to continue to adapt when the source audio is absent or has reduced amplitude, and wherein the processing circuit further controls the controllable noise source in conformity with an output of the secondary path adaptive filter.
2. The personal audio device of claim 1, wherein the processing circuit measures an amplitude of the output of the secondary path adaptive filter and changes the controllable noise source if the amplitude of the output of the secondary path adaptive filter exceeds a threshold amplitude.
3. The personal audio device of claim 2, wherein the processing circuit adjusts a gain applied to the noise signal if the amplitude of the output of the secondary path adaptive filter exceeds the threshold amplitude.
4. The personal audio device of claim 2, wherein the processing circuit disables injection of the noise signal if the amplitude of the output of the secondary path adaptive filter exceeds the threshold amplitude.
5. The personal audio device of claim 2, wherein the processing circuit further determines the threshold amplitude from an amplitude of the error signal, wherein the threshold amplitude is dynamically adjusted according to the amplitude of the error signal.
6. The personal audio device of claim 5, wherein the threshold amplitude is a level 20 dB below the amplitude of the error signal.
7. The personal audio device of claim 1, wherein the processing circuit detects that an amplitude of the source audio is below a threshold amplitude and only changes the controllable noise source if the amplitude of the source audio is below the threshold amplitude.
8. The personal audio device of claim 1, wherein the processing circuit implements an adaptive filter having a response that generates the anti-noise signal from the reference signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit shapes the response of the adaptive filter in conformity with the error signal and the reference microphone signal.
9. A method of canceling ambient audio sounds in the proximity of a transducer of a personal audio device, the method comprising:
first measuring ambient audio sounds with a reference microphone to produce a reference microphone signal;
second measuring an output of the transducer and the ambient audio sounds at the transducer with an error microphone;
adaptively generating an anti-noise signal from a result of the first measuring and the second measuring for countering the effects of ambient audio sounds at an acoustic output of the transducer;
combining the anti-noise signal with a source audio signal to generate an audio signal provided to the transducer;
shaping a copy of the source audio with a secondary path response to generate shaped source audio;
removing the result of the shaping the copy of the source audio from the error microphone signal to produce an error signal indicative of the combined anti-noise and ambient audio sounds delivered to the listener;
generating a noise signal;
determining whether source audio of sufficient amplitude is present in the source audio signal using a source audio detector having an input coupled to the source audio signal;
selectively, in response to determining that source audio of sufficient amplitude is not present, injecting the noise signal into the secondary path adaptive filter in place of or in combination with the source audio signal and wherein the combining further combines the noise in place of or in combination with the source audio signal to cause the secondary path adaptive filter to continue to adapt when the source audio is absent or has reduced amplitude; and
controlling the controllable noise source in conformity with an output of the secondary path adaptive filter.
10. The method of claim 9, further comprising measuring an amplitude of the output of the secondary path adaptive filter, wherein the controlling the controllable noise source adjusts the controllable noise source if the amplitude of the output of the secondary path adaptive filter exceeds a threshold amplitude.
11. The method of claim 10, wherein the controlling the controllable noise source adjusts a gain applied to the noise signal if the amplitude of the output of the secondary path adaptive filter exceeds the threshold amplitude.
12. The method of claim 10, wherein the controlling the controllable noise source disables injection of the noise signal if the amplitude of the output of the secondary path adaptive filter exceeds the threshold amplitude.
13. The method of claim 10, further comprising determining the threshold amplitude from an amplitude of the error signal, wherein the threshold amplitude is dynamically adjusted according to the amplitude of the error signal.
14. The method of claim 13, wherein the threshold amplitude is a level 20 dB below the amplitude of the error signal.
15. The method of claim 9, further comprising detecting that an amplitude of the source audio is below a threshold amplitude, and wherein the controlling the controllable noise source only changes the controllable noise source if the amplitude of the source audio is below the threshold amplitude.
16. The method of claim 9, wherein the adaptively generating adapts a response of an adaptive filter that filters an output of the reference microphone to generate the anti-noise signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the adaptively generating shapes the response of the adaptive filter in conformity with the error signal and the reference microphone signal.
17. An integrated circuit for implementing at least a portion of a personal audio device, comprising:
an output for providing a signal to a transducer including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer;
a first combiner for combining a source audio signal containing the source audio and the anti-noise signal to provide an output signal for reproduction by the transducer;
a reference microphone input for receiving a reference microphone signal indicative of the ambient audio sounds;
an error microphone input for receiving an error microphone signal indicative of the acoustic output of the transducer and the ambient audio sounds at the transducer;
a controllable noise source for providing a noise signal;
a source audio detector having an input coupled to the source audio signal for determining whether source audio of sufficient amplitude is present in the source audio signal; and
a processing circuit that generates the anti-noise signal from the reference microphone signal to reduce the presence of the ambient audio sounds heard by the listener in conformity with an error signal and the reference microphone signal, wherein the processing circuit implements a secondary path adaptive filter having a secondary path response that shapes the source audio to generate shaped source audio and a second combiner that removes the shaped source audio from the error microphone signal to provide the error signal, and wherein the processing circuit, in response to the source audio detector determining that source audio of sufficient amplitude is not present in the source audio signal, selectively injects noise from the controllable noise source into the secondary path adaptive filter and further injects the noise into the first combiner in place of or in combination with the source audio signal to cause the secondary path adaptive filter to continue to adapt when the source audio is absent or has reduced amplitude, and wherein the processing circuit further controls the controllable noise source in conformity with an output of the secondary path adaptive filter.
18. The integrated circuit of claim 17, wherein the processing circuit measures an amplitude of the output of the secondary path adaptive filter and changes the controllable noise source if the amplitude of the output of the secondary path adaptive filter exceeds a threshold amplitude.
19. The integrated circuit of claim 18, wherein the processing circuit adjusts a gain applied to the noise signal if the amplitude of the output of the secondary path adaptive filter exceeds the threshold amplitude.
20. The integrated circuit of claim 18, wherein the processing circuit disables injection of the noise signal if the amplitude of the output of the secondary path adaptive filter exceeds the threshold amplitude.
21. The integrated circuit of claim 18, wherein the processing circuit further determines the threshold amplitude from an amplitude of the error signal, wherein the threshold amplitude is dynamically adjusted according to the amplitude of the error signal.
22. The integrated circuit of claim 21, wherein the threshold amplitude is a level 20 dB below the amplitude of the error signal.
23. The integrated circuit of claim 17, wherein the processing circuit detects that an amplitude of the source audio is below a threshold amplitude and only changes the controllable noise source if the amplitude of the source audio is below the threshold amplitude.
24. The integrated circuit of claim 17, wherein the processing circuit implements an adaptive filter having a response that generates the anti-noise signal from the reference signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit shapes the response of the adaptive filter in conformity with the error signal and the reference microphone signal.
US13/458,585 2011-06-03 2012-04-27 Continuous adaptation of secondary path adaptive response in noise-canceling personal audio devices Active 2034-01-24 US9214150B2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US201161493162P true 2011-06-03 2011-06-03
US13/458,585 US9214150B2 (en) 2011-06-03 2012-04-27 Continuous adaptation of secondary path adaptive response in noise-canceling personal audio devices

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US13/458,585 US9214150B2 (en) 2011-06-03 2012-04-27 Continuous adaptation of secondary path adaptive response in noise-canceling personal audio devices
CN201280038454.7A CN103718238B (en) 2011-06-03 2012-05-24 Adjusting continuously of secondary path adaptive response in individual speech ciphering equipment is eliminated at noise
PCT/US2012/039336 WO2012166511A2 (en) 2011-06-03 2012-05-24 Continuous adaptation of secondary path adaptive response in noise-canceling personal audio devices
KR1020137034481A KR101918466B1 (en) 2011-06-03 2012-05-24 Continuous adaptation of secondary path adaptive response in noise-canceling personal audio devices
JP2014513582A JP6106164B2 (en) 2011-06-03 2012-05-24 Continuous adaptation of secondary path adaptive responses in noise-canceling personal audio devices
EP12725254.2A EP2715716B1 (en) 2011-06-03 2012-05-24 Continuous adaptation of secondary path adaptive response in noise-canceling personal audio devices

Publications (2)

Publication Number Publication Date
US20120308027A1 US20120308027A1 (en) 2012-12-06
US9214150B2 true US9214150B2 (en) 2015-12-15

Family

ID=46201865

Family Applications (1)

Application Number Title Priority Date Filing Date
US13/458,585 Active 2034-01-24 US9214150B2 (en) 2011-06-03 2012-04-27 Continuous adaptation of secondary path adaptive response in noise-canceling personal audio devices

Country Status (6)

Country Link
US (1) US9214150B2 (en)
EP (1) EP2715716B1 (en)
JP (1) JP6106164B2 (en)
KR (1) KR101918466B1 (en)
CN (1) CN103718238B (en)
WO (1) WO2012166511A2 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150271602A1 (en) * 2012-11-02 2015-09-24 Bose Corporation Binaural Telepresence
US10249284B2 (en) 2011-06-03 2019-04-02 Cirrus Logic, Inc. Bandlimiting anti-noise in personal audio devices having adaptive noise cancellation (ANC)

Families Citing this family (51)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103270552B (en) 2010-12-03 2016-06-22 美国思睿逻辑有限公司 The Supervised Control of the adaptability noise killer in individual's voice device
US8908877B2 (en) 2010-12-03 2014-12-09 Cirrus Logic, Inc. Ear-coupling detection and adjustment of adaptive response in noise-canceling in personal audio devices
US8958571B2 (en) 2011-06-03 2015-02-17 Cirrus Logic, Inc. MIC covering detection in personal audio devices
US8848936B2 (en) 2011-06-03 2014-09-30 Cirrus Logic, Inc. Speaker damage prevention in adaptive noise-canceling personal audio devices
US8948407B2 (en) 2011-06-03 2015-02-03 Cirrus Logic, Inc. Bandlimiting anti-noise in personal audio devices having adaptive noise cancellation (ANC)
US9318094B2 (en) 2011-06-03 2016-04-19 Cirrus Logic, Inc. Adaptive noise canceling architecture for a personal audio device
US9076431B2 (en) 2011-06-03 2015-07-07 Cirrus Logic, Inc. Filter architecture for an adaptive noise canceler in a personal audio device
US9325821B1 (en) * 2011-09-30 2016-04-26 Cirrus Logic, Inc. Sidetone management in an adaptive noise canceling (ANC) system including secondary path modeling
US9142205B2 (en) 2012-04-26 2015-09-22 Cirrus Logic, Inc. Leakage-modeling adaptive noise canceling for earspeakers
US9014387B2 (en) 2012-04-26 2015-04-21 Cirrus Logic, Inc. Coordinated control of adaptive noise cancellation (ANC) among earspeaker channels
US9123321B2 (en) 2012-05-10 2015-09-01 Cirrus Logic, Inc. Sequenced adaptation of anti-noise generator response and secondary path response in an adaptive noise canceling system
US9318090B2 (en) 2012-05-10 2016-04-19 Cirrus Logic, Inc. Downlink tone detection and adaptation of a secondary path response model in an adaptive noise canceling system
US9319781B2 (en) 2012-05-10 2016-04-19 Cirrus Logic, Inc. Frequency and direction-dependent ambient sound handling in personal audio devices having adaptive noise cancellation (ANC)
US9082387B2 (en) 2012-05-10 2015-07-14 Cirrus Logic, Inc. Noise burst adaptation of secondary path adaptive response in noise-canceling personal audio devices
US9076427B2 (en) 2012-05-10 2015-07-07 Cirrus Logic, Inc. Error-signal content controlled adaptation of secondary and leakage path models in noise-canceling personal audio devices
US9532139B1 (en) 2012-09-14 2016-12-27 Cirrus Logic, Inc. Dual-microphone frequency amplitude response self-calibration
US9330652B2 (en) * 2012-09-24 2016-05-03 Apple Inc. Active noise cancellation using multiple reference microphone signals
US9107010B2 (en) 2013-02-08 2015-08-11 Cirrus Logic, Inc. Ambient noise root mean square (RMS) detector
US9369798B1 (en) 2013-03-12 2016-06-14 Cirrus Logic, Inc. Internal dynamic range control in an adaptive noise cancellation (ANC) system
US9106989B2 (en) 2013-03-13 2015-08-11 Cirrus Logic, Inc. Adaptive-noise canceling (ANC) effectiveness estimation and correction in a personal audio device
US9215749B2 (en) 2013-03-14 2015-12-15 Cirrus Logic, Inc. Reducing an acoustic intensity vector with adaptive noise cancellation with two error microphones
US9414150B2 (en) 2013-03-14 2016-08-09 Cirrus Logic, Inc. Low-latency multi-driver adaptive noise canceling (ANC) system for a personal audio device
US9635480B2 (en) 2013-03-15 2017-04-25 Cirrus Logic, Inc. Speaker impedance monitoring
US9502020B1 (en) 2013-03-15 2016-11-22 Cirrus Logic, Inc. Robust adaptive noise canceling (ANC) in a personal audio device
US9208771B2 (en) 2013-03-15 2015-12-08 Cirrus Logic, Inc. Ambient noise-based adaptation of secondary path adaptive response in noise-canceling personal audio devices
US9467776B2 (en) 2013-03-15 2016-10-11 Cirrus Logic, Inc. Monitoring of speaker impedance to detect pressure applied between mobile device and ear
US10206032B2 (en) * 2013-04-10 2019-02-12 Cirrus Logic, Inc. Systems and methods for multi-mode adaptive noise cancellation for audio headsets
US9066176B2 (en) 2013-04-15 2015-06-23 Cirrus Logic, Inc. Systems and methods for adaptive noise cancellation including dynamic bias of coefficients of an adaptive noise cancellation system
US9462376B2 (en) * 2013-04-16 2016-10-04 Cirrus Logic, Inc. Systems and methods for hybrid adaptive noise cancellation
US9478210B2 (en) * 2013-04-17 2016-10-25 Cirrus Logic, Inc. Systems and methods for hybrid adaptive noise cancellation
US9460701B2 (en) 2013-04-17 2016-10-04 Cirrus Logic, Inc. Systems and methods for adaptive noise cancellation by biasing anti-noise level
US9578432B1 (en) 2013-04-24 2017-02-21 Cirrus Logic, Inc. Metric and tool to evaluate secondary path design in adaptive noise cancellation systems
US9264808B2 (en) 2013-06-14 2016-02-16 Cirrus Logic, Inc. Systems and methods for detection and cancellation of narrow-band noise
US9392364B1 (en) 2013-08-15 2016-07-12 Cirrus Logic, Inc. Virtual microphone for adaptive noise cancellation in personal audio devices
US9666176B2 (en) * 2013-09-13 2017-05-30 Cirrus Logic, Inc. Systems and methods for adaptive noise cancellation by adaptively shaping internal white noise to train a secondary path
US9620101B1 (en) 2013-10-08 2017-04-11 Cirrus Logic, Inc. Systems and methods for maintaining playback fidelity in an audio system with adaptive noise cancellation
US10382864B2 (en) 2013-12-10 2019-08-13 Cirrus Logic, Inc. Systems and methods for providing adaptive playback equalization in an audio device
US10219071B2 (en) 2013-12-10 2019-02-26 Cirrus Logic, Inc. Systems and methods for bandlimiting anti-noise in personal audio devices having adaptive noise cancellation
US9704472B2 (en) 2013-12-10 2017-07-11 Cirrus Logic, Inc. Systems and methods for sharing secondary path information between audio channels in an adaptive noise cancellation system
US9369557B2 (en) 2014-03-05 2016-06-14 Cirrus Logic, Inc. Frequency-dependent sidetone calibration
US9479860B2 (en) 2014-03-07 2016-10-25 Cirrus Logic, Inc. Systems and methods for enhancing performance of audio transducer based on detection of transducer status
US9648410B1 (en) 2014-03-12 2017-05-09 Cirrus Logic, Inc. Control of audio output of headphone earbuds based on the environment around the headphone earbuds
US9319784B2 (en) * 2014-04-14 2016-04-19 Cirrus Logic, Inc. Frequency-shaped noise-based adaptation of secondary path adaptive response in noise-canceling personal audio devices
US9609416B2 (en) 2014-06-09 2017-03-28 Cirrus Logic, Inc. Headphone responsive to optical signaling
US10181315B2 (en) 2014-06-13 2019-01-15 Cirrus Logic, Inc. Systems and methods for selectively enabling and disabling adaptation of an adaptive noise cancellation system
US9478212B1 (en) 2014-09-03 2016-10-25 Cirrus Logic, Inc. Systems and methods for use of adaptive secondary path estimate to control equalization in an audio device
US9552805B2 (en) 2014-12-19 2017-01-24 Cirrus Logic, Inc. Systems and methods for performance and stability control for feedback adaptive noise cancellation
US10026388B2 (en) 2015-08-20 2018-07-17 Cirrus Logic, Inc. Feedback adaptive noise cancellation (ANC) controller and method having a feedback response partially provided by a fixed-response filter
US9578415B1 (en) 2015-08-21 2017-02-21 Cirrus Logic, Inc. Hybrid adaptive noise cancellation system with filtered error microphone signal
KR101699339B1 (en) * 2015-09-14 2017-01-24 전자부품연구원 Apparatus for outputting audio signal and method for controlling active noise
US10013966B2 (en) 2016-03-15 2018-07-03 Cirrus Logic, Inc. Systems and methods for adaptive active noise cancellation for multiple-driver personal audio device

Citations (206)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5251263A (en) 1992-05-22 1993-10-05 Andrea Electronics Corporation Adaptive noise cancellation and speech enhancement system and apparatus therefor
US5278913A (en) 1992-07-28 1994-01-11 Nelson Industries, Inc. Active acoustic attenuation system with power limiting
US5321759A (en) 1992-04-29 1994-06-14 General Motors Corporation Active noise control system for attenuating engine generated noise
JPH06186985A (en) 1992-12-21 1994-07-08 Nissan Motor Co Ltd Active noise controller
US5337365A (en) 1991-08-30 1994-08-09 Nissan Motor Co., Ltd. Apparatus for actively reducing noise for interior of enclosed space
US5359662A (en) 1992-04-29 1994-10-25 General Motors Corporation Active noise control system
US5410605A (en) 1991-07-05 1995-04-25 Honda Giken Kogyo Kabushiki Kaisha Active vibration control system
US5425105A (en) 1993-04-27 1995-06-13 Hughes Aircraft Company Multiple adaptive filter active noise canceller
US5445517A (en) 1992-10-14 1995-08-29 Matsushita Electric Industrial Co., Ltd. Adaptive noise silencing system of combustion apparatus
US5465413A (en) 1993-03-05 1995-11-07 Trimble Navigation Limited Adaptive noise cancellation
US5548681A (en) 1991-08-13 1996-08-20 Kabushiki Kaisha Toshiba Speech dialogue system for realizing improved communication between user and system
US5586190A (en) 1994-06-23 1996-12-17 Digisonix, Inc. Active adaptive control system with weight update selective leakage
US5640450A (en) 1994-07-08 1997-06-17 Kokusai Electric Co., Ltd. Speech circuit controlling sidetone signal by background noise level
US5699437A (en) 1995-08-29 1997-12-16 United Technologies Corporation Active noise control system using phased-array sensors
US5706344A (en) 1996-03-29 1998-01-06 Digisonix, Inc. Acoustic echo cancellation in an integrated audio and telecommunication system
US5740256A (en) 1995-12-15 1998-04-14 U.S. Philips Corporation Adaptive noise cancelling arrangement, a noise reduction system and a transceiver
US5768124A (en) 1992-10-21 1998-06-16 Lotus Cars Limited Adaptive control system
US5815582A (en) 1994-12-02 1998-09-29 Noise Cancellation Technologies, Inc. Active plus selective headset
US5832095A (en) 1996-10-18 1998-11-03 Carrier Corporation Noise canceling system
WO1999011045A1 (en) 1997-08-21 1999-03-04 The Secretary Of State For The Environment, Transport And The Regions Telephone handset noise suppression
US5946391A (en) 1995-11-24 1999-08-31 Nokia Mobile Phones Limited Telephones with talker sidetone
US5991418A (en) 1996-12-17 1999-11-23 Texas Instruments Incorporated Off-line path modeling circuitry and method for off-line feedback path modeling and off-line secondary path modeling
US6041126A (en) 1995-07-24 2000-03-21 Matsushita Electric Industrial Co., Ltd. Noise cancellation system
US6118878A (en) 1993-06-23 2000-09-12 Noise Cancellation Technologies, Inc. Variable gain active noise canceling system with improved residual noise sensing
US6219427B1 (en) 1997-11-18 2001-04-17 Gn Resound As Feedback cancellation improvements
US6278786B1 (en) 1997-07-29 2001-08-21 Telex Communications, Inc. Active noise cancellation aircraft headset system
US6282176B1 (en) 1998-03-20 2001-08-28 Cirrus Logic, Inc. Full-duplex speakerphone circuit including a supplementary echo suppressor
US20010053228A1 (en) 1997-08-18 2001-12-20 Owen Jones Noise cancellation system for active headsets
US20020003887A1 (en) * 2000-07-05 2002-01-10 Nanyang Technological University Active noise control system with on-line secondary path modeling
US6418228B1 (en) 1998-07-16 2002-07-09 Matsushita Electric Industrial Co., Ltd. Noise control system
US6434247B1 (en) 1999-07-30 2002-08-13 Gn Resound A/S Feedback cancellation apparatus and methods utilizing adaptive reference filter mechanisms
US6434246B1 (en) 1995-10-10 2002-08-13 Gn Resound As Apparatus and methods for combining audio compression and feedback cancellation in a hearing aid
US6522746B1 (en) 1999-11-03 2003-02-18 Tellabs Operations, Inc. Synchronization of voice boundaries and their use by echo cancellers in a voice processing system
WO2003015074A1 (en) 2001-08-08 2003-02-20 Nanyang Technological University,Centre For Signal Processing. Active noise control system with on-line secondary path modeling
WO2003015275A1 (en) 2001-08-07 2003-02-20 Dspfactory, Ltd. Sub-band adaptive signal processing in an oversampled filterbank
US20030063759A1 (en) 2001-08-08 2003-04-03 Brennan Robert L. Directional audio signal processing using an oversampled filterbank
US20030072439A1 (en) 2000-01-27 2003-04-17 Gupta Samir K. System and method for implementation of an echo canceller
US20030185403A1 (en) 2000-03-07 2003-10-02 Alastair Sibbald Method of improving the audibility of sound from a louspeaker located close to an ear
US6683960B1 (en) 1998-04-15 2004-01-27 Fujitsu Limited Active noise control apparatus
WO2004009007A1 (en) 2002-07-19 2004-01-29 The Penn State Research Foundation A linear independent method for noninvasive online secondary path modeling
WO2004017303A1 (en) 2002-08-16 2004-02-26 Dspfactory Ltd. Method and system for processing subband signals using adaptive filters
US20040047464A1 (en) 2002-09-11 2004-03-11 Zhuliang Yu Adaptive noise cancelling microphone system
US20040120535A1 (en) 1999-09-10 2004-06-24 Starkey Laboratories, Inc. Audio signal processing
US6766292B1 (en) 2000-03-28 2004-07-20 Tellabs Operations, Inc. Relative noise ratio weighting techniques for adaptive noise cancellation
US6768795B2 (en) 2001-01-11 2004-07-27 Telefonaktiebolaget Lm Ericsson (Publ) Side-tone control within a telecommunication instrument
US20040165736A1 (en) 2003-02-21 2004-08-26 Phil Hetherington Method and apparatus for suppressing wind noise
US20040167777A1 (en) 2003-02-21 2004-08-26 Hetherington Phillip A. System for suppressing wind noise
US20040202333A1 (en) 2003-04-08 2004-10-14 Csermak Brian D. Hearing instrument with self-diagnostics
GB2401744A (en) 2003-05-14 2004-11-17 Ultra Electronics Ltd An adaptive noise control unit with feedback compensation
US20040240677A1 (en) 2003-05-29 2004-12-02 Masahide Onishi Active noise control system
US20040242160A1 (en) 2003-05-30 2004-12-02 Nokia Corporation Mobile phone for voice adaptation in socially sensitive environment
US20040264706A1 (en) 2001-06-22 2004-12-30 Ray Laura R Tuned feedforward LMS filter with feedback control
US20050004796A1 (en) 2003-02-27 2005-01-06 Telefonaktiebolaget Lm Ericsson (Publ), Audibility enhancement
US20050018862A1 (en) 2001-06-29 2005-01-27 Fisher Michael John Amiel Digital signal processing system and method for a telephony interface apparatus
US6850617B1 (en) 1999-12-17 2005-02-01 National Semiconductor Corporation Telephone receiver circuit with dynamic sidetone signal generator controlled by voice activity detection
US20050117754A1 (en) 2003-12-02 2005-06-02 Atsushi Sakawaki Active noise cancellation helmet, motor vehicle system including the active noise cancellation helmet, and method of canceling noise in helmet
US6940982B1 (en) 2001-03-28 2005-09-06 Lsi Logic Corporation Adaptive noise cancellation (ANC) for DVD systems
US20050207585A1 (en) 2004-03-17 2005-09-22 Markus Christoph Active noise tuning system
US20050240401A1 (en) 2004-04-23 2005-10-27 Acoustic Technologies, Inc. Noise suppression based on Bark band weiner filtering and modified doblinger noise estimate
US20060035593A1 (en) 2004-08-12 2006-02-16 Motorola, Inc. Noise and interference reduction in digitized signals
US20060055910A1 (en) 2004-08-27 2006-03-16 Jong-Haw Lee Exposure apparatus adapted to detect abnormal operating phenomenon
US20060069556A1 (en) 2004-09-15 2006-03-30 Nadjar Hamid S Method and system for active noise cancellation
US7058463B1 (en) 2000-12-29 2006-06-06 Nokia Corporation Method and apparatus for implementing a class D driver and speaker system
US20060153400A1 (en) 2005-01-12 2006-07-13 Yamaha Corporation Microphone and sound amplification system
US7103188B1 (en) 1993-06-23 2006-09-05 Owen Jones Variable gain active noise cancelling system with improved residual noise sensing
WO2007007916A1 (en) 2005-07-14 2007-01-18 Matsushita Electric Industrial Co., Ltd. Transmitting apparatus and method capable of generating a warning depending on sound types
US20070030989A1 (en) 2005-08-02 2007-02-08 Gn Resound A/S Hearing aid with suppression of wind noise
US20070033029A1 (en) 2005-05-26 2007-02-08 Yamaha Hatsudoki Kabushiki Kaisha Noise cancellation helmet, motor vehicle system including the noise cancellation helmet, and method of canceling noise in helmet
US20070038441A1 (en) 2005-08-09 2007-02-15 Honda Motor Co., Ltd. Active noise control system
US7181030B2 (en) 2002-01-12 2007-02-20 Oticon A/S Wind noise insensitive hearing aid
US20070047742A1 (en) 2005-08-26 2007-03-01 Step Communications Corporation, A Nevada Corporation Method and system for enhancing regional sensitivity noise discrimination
US20070053524A1 (en) 2003-05-09 2007-03-08 Tim Haulick Method and system for communication enhancement in a noisy environment
US20070076896A1 (en) 2005-09-28 2007-04-05 Kabushiki Kaisha Toshiba Active noise-reduction control apparatus and method
US20070154031A1 (en) 2006-01-05 2007-07-05 Audience, Inc. System and method for utilizing inter-microphone level differences for speech enhancement
WO2007113487A1 (en) 2006-04-01 2007-10-11 Wolfson Microelectronics Plc Ambient noise-reduction control system
US20070258597A1 (en) 2004-08-24 2007-11-08 Oticon A/S Low Frequency Phase Matching for Microphones
US20070297620A1 (en) 2006-06-27 2007-12-27 Choy Daniel S J Methods and Systems for Producing a Zone of Reduced Background Noise
EP1880699A2 (en) 2004-08-25 2008-01-23 Phonak AG Method for manufacturing an earplug
US20080019548A1 (en) 2006-01-30 2008-01-24 Audience, Inc. System and method for utilizing omni-directional microphones for speech enhancement
US7330739B2 (en) 2005-03-31 2008-02-12 Nxp B.V. Method and apparatus for providing a sidetone in a wireless communication device
US7365669B1 (en) 2007-03-28 2008-04-29 Cirrus Logic, Inc. Low-delay signal processing based on highly oversampled digital processing
US20080101589A1 (en) 2006-10-31 2008-05-01 Palm, Inc. Audio output using multiple speakers
US20080107281A1 (en) 2006-11-02 2008-05-08 Masahito Togami Acoustic echo canceller system
US20080144853A1 (en) 2006-12-06 2008-06-19 Sommerfeldt Scott D Secondary Path Modeling for Active Noise Control
EP1947642A1 (en) 2007-01-16 2008-07-23 Harman/Becker Automotive Systems GmbH Active noise control system
US20080177532A1 (en) 2007-01-22 2008-07-24 D.S.P. Group Ltd. Apparatus and methods for enhancement of speech
US20080226098A1 (en) 2005-04-29 2008-09-18 Tim Haulick Detection and suppression of wind noise in microphone signals
US20080240455A1 (en) 2007-03-30 2008-10-02 Honda Motor Co., Ltd. Active noise control apparatus
US20080240457A1 (en) 2007-03-30 2008-10-02 Honda Motor Co., Ltd. Active noise control apparatus
US20080240413A1 (en) 2007-04-02 2008-10-02 Microsoft Corporation Cross-correlation based echo canceller controllers
US20090012783A1 (en) 2007-07-06 2009-01-08 Audience, Inc. System and method for adaptive intelligent noise suppression
US20090041260A1 (en) 2007-08-10 2009-02-12 Oticon A/S Active noise cancellation in hearing devices
US20090046867A1 (en) 2006-04-12 2009-02-19 Wolfson Microelectronics Plc Digtal Circuit Arrangements for Ambient Noise-Reduction
US20090060222A1 (en) 2007-09-05 2009-03-05 Samsung Electronics Co., Ltd. Sound zoom method, medium, and apparatus
US20090080670A1 (en) 2007-09-24 2009-03-26 Sound Innovations Inc. In-Ear Digital Electronic Noise Cancelling and Communication Device
US20090086990A1 (en) 2007-09-27 2009-04-02 Markus Christoph Active noise control using bass management
GB2455828A (en) 2007-12-21 2009-06-24 Wolfson Microelectronics Plc Noise cancellation system with adaptive filter and two different sample rates
GB2455821A (en) 2007-12-21 2009-06-24 Wolfson Microelectronics Plc Active noise cancellation system with split digital filter
GB2455824A (en) 2007-12-21 2009-06-24 Wolfson Microelectronics Plc Active noise cancellation system turns off or lessens cancellation during voiceless intervals
US20090175466A1 (en) 2002-02-05 2009-07-09 Mh Acoustics, Llc Noise-reducing directional microphone array
US20090196429A1 (en) 2008-01-31 2009-08-06 Qualcomm Incorporated Signaling microphone covering to the user
US20090220107A1 (en) 2008-02-29 2009-09-03 Audience, Inc. System and method for providing single microphone noise suppression fallback
US20090238369A1 (en) 2008-03-18 2009-09-24 Qualcomm Incorporated Systems and methods for detecting wind noise using multiple audio sources
US20090245529A1 (en) 2008-03-28 2009-10-01 Sony Corporation Headphone device, signal processing device, and signal processing method
US20090254340A1 (en) 2008-04-07 2009-10-08 Cambridge Silicon Radio Limited Noise Reduction
US20090290718A1 (en) 2008-05-21 2009-11-26 Philippe Kahn Method and Apparatus for Adjusting Audio for a User Environment
US20090296965A1 (en) 2008-05-27 2009-12-03 Mariko Kojima Hearing aid, and hearing-aid processing method and integrated circuit for hearing aid
US20090304200A1 (en) 2008-06-09 2009-12-10 Samsung Electronics Co., Ltd. Adaptive mode control apparatus and method for adaptive beamforming based on detection of user direction sound
EP2133866A1 (en) 2008-06-13 2009-12-16 Harman Becker Automotive Systems GmbH Adaptive noise control system
US20090311979A1 (en) 2008-06-12 2009-12-17 Atheros Communications, Inc. Polar modulator with path delay compensation
US20100014683A1 (en) 2008-07-15 2010-01-21 Panasonic Corporation Noise reduction device
US20100061564A1 (en) 2007-02-07 2010-03-11 Richard Clemow Ambient noise reduction system
US7680456B2 (en) 2005-02-16 2010-03-16 Texas Instruments Incorporated Methods and apparatus to perform signal removal in a low intermediate frequency receiver
US20100069114A1 (en) 2008-09-15 2010-03-18 Lee Michael M Sidetone selection for headsets or earphones
US20100082339A1 (en) 2008-09-30 2010-04-01 Alon Konchitsky Wind Noise Reduction
US20100098263A1 (en) 2008-10-20 2010-04-22 Pan Davis Y Active noise reduction adaptive filter leakage adjusting
US20100098265A1 (en) 2008-10-20 2010-04-22 Pan Davis Y Active noise reduction adaptive filter adaptation rate adjusting
US20100124337A1 (en) 2008-11-20 2010-05-20 Harman International Industries, Incorporated Quiet zone control system
US20100124336A1 (en) 2008-11-20 2010-05-20 Harman International Industries, Incorporated System for active noise control with audio signal compensation
US20100131269A1 (en) 2008-11-24 2010-05-27 Qualcomm Incorporated Systems, methods, apparatus, and computer program products for enhanced active noise cancellation
US20100142715A1 (en) 2008-09-16 2010-06-10 Personics Holdings Inc. Sound Library and Method
US20100150367A1 (en) 2005-10-21 2010-06-17 Ko Mizuno Noise control device
US7742790B2 (en) 2006-05-23 2010-06-22 Alon Konchitsky Environmental noise reduction and cancellation for a communication device including for a wireless and cellular telephone
US20100158330A1 (en) 2005-09-12 2010-06-24 Dvp Technologies Ltd. Medical Image Processing
US20100166203A1 (en) 2007-03-19 2010-07-01 Sennheiser Electronic Gmbh & Co. Kg Headset
US20100195844A1 (en) 2009-01-30 2010-08-05 Markus Christoph Adaptive noise control system
US20100195838A1 (en) 2009-02-03 2010-08-05 Nokia Corporation Apparatus including microphone arrangements
US20100207317A1 (en) 2005-06-14 2010-08-19 Glory, Ltd. Paper-sheet feeding device with kicker roller
US20100246855A1 (en) 2009-03-31 2010-09-30 Apple Inc. Dynamic audio parameter adjustment using touch sensing
EP2237573A1 (en) 2009-04-02 2010-10-06 Oticon A/S Adaptive feedback cancellation method and apparatus therefor
WO2010117714A1 (en) 2009-03-30 2010-10-14 Bose Corporation Personal acoustic device position determination
US7817808B2 (en) 2007-07-19 2010-10-19 Alon Konchitsky Dual adaptive structure for speech enhancement
US20100274564A1 (en) 2009-04-28 2010-10-28 Pericles Nicholas Bakalos Coordinated anr reference sound compression
US20100272283A1 (en) 2009-04-28 2010-10-28 Carreras Ricardo F Digital high frequency phase compensation
US20100272276A1 (en) 2009-04-28 2010-10-28 Carreras Ricardo F ANR Signal Processing Topology
US20100284546A1 (en) 2005-08-18 2010-11-11 Debrunner Victor Active noise control algorithm that requires no secondary path identification based on the SPR property
US20100291891A1 (en) 2008-01-25 2010-11-18 Nxp B.V. Improvements in or relating to radio receivers
US20100296668A1 (en) 2009-04-23 2010-11-25 Qualcomm Incorporated Systems, methods, apparatus, and computer-readable media for automatic control of active noise cancellation
US20100296666A1 (en) 2009-05-25 2010-11-25 National Chin-Yi University Of Technology Apparatus and method for noise cancellation in voice communication
US20100310086A1 (en) 2007-12-21 2010-12-09 Anthony James Magrath Noise cancellation system with lower rate emulation
US20100322430A1 (en) 2009-06-17 2010-12-23 Sony Ericsson Mobile Communications Ab Portable communication device and a method of processing signals therein
US20110007907A1 (en) 2009-07-10 2011-01-13 Qualcomm Incorporated Systems, methods, apparatus, and computer-readable media for adaptive active noise cancellation
US20110106533A1 (en) 2008-06-30 2011-05-05 Dolby Laboratories Licensing Corporation Multi-Microphone Voice Activity Detector
US20110129098A1 (en) 2009-10-28 2011-06-02 Delano Cary L Active noise cancellation
US20110130176A1 (en) 2008-06-27 2011-06-02 Anthony James Magrath Noise cancellation system
US20110142247A1 (en) 2008-07-29 2011-06-16 Dolby Laboratories Licensing Corporation MMethod for Adaptive Control and Equalization of Electroacoustic Channels
US20110144984A1 (en) 2006-05-11 2011-06-16 Alon Konchitsky Voice coder with two microphone system and strategic microphone placement to deter obstruction for a digital communication device
US20110158419A1 (en) 2009-12-30 2011-06-30 Lalin Theverapperuma Adaptive digital noise canceller
US20110206214A1 (en) 2010-02-25 2011-08-25 Markus Christoph Active noise reduction system
US8019050B2 (en) 2007-01-03 2011-09-13 Motorola Solutions, Inc. Method and apparatus for providing feedback of vocal quality to a user
US20110222698A1 (en) 2010-03-12 2011-09-15 Panasonic Corporation Noise reduction device
US20110249826A1 (en) 2008-12-18 2011-10-13 Koninklijke Philips Electronics N.V. Active audio noise cancelling
US20110288860A1 (en) 2010-05-20 2011-11-24 Qualcomm Incorporated Systems, methods, apparatus, and computer-readable media for processing of speech signals using head-mounted microphone pair
US20110293103A1 (en) 2010-06-01 2011-12-01 Qualcomm Incorporated Systems, methods, devices, apparatus, and computer program products for audio equalization
US20110299695A1 (en) 2010-06-04 2011-12-08 Apple Inc. Active noise cancellation decisions in a portable audio device
EP2395501A1 (en) 2010-06-14 2011-12-14 Harman Becker Automotive Systems GmbH Adaptive noise control
EP2395500A1 (en) 2010-06-11 2011-12-14 Nxp B.V. Audio device
US20110317848A1 (en) 2010-06-23 2011-12-29 Motorola, Inc. Microphone Interference Detection Method and Apparatus
GB2484722A (en) 2010-10-21 2012-04-25 Wolfson Microelectronics Plc Control of a noise cancellation system according to a detected position of an audio device
US20120135787A1 (en) 2010-11-25 2012-05-31 Kyocera Corporation Mobile phone and echo reduction method therefore
US20120140943A1 (en) 2010-12-03 2012-06-07 Hendrix Jon D Oversight control of an adaptive noise canceler in a personal audio device
US20120140917A1 (en) 2010-06-04 2012-06-07 Apple Inc. Active noise cancellation decisions using a degraded reference
US20120140942A1 (en) 2010-12-01 2012-06-07 Dialog Semiconductor Gmbh Reduced delay digital active noise cancellation
US20120155666A1 (en) 2010-12-16 2012-06-21 Nair Vijayakumaran V Adaptive noise cancellation
US20120170766A1 (en) 2011-01-05 2012-07-05 Cambridge Silicon Radio Limited ANC For BT Headphones
US20120207317A1 (en) 2010-12-03 2012-08-16 Ali Abdollahzadeh Milani Ear-coupling detection and adjustment of adaptive response in noise-canceling in personal audio devices
US8249262B2 (en) 2009-04-27 2012-08-21 Siemens Medical Instruments Pte. Ltd. Device for acoustically analyzing a hearing device and analysis method
US20120215519A1 (en) 2011-02-23 2012-08-23 Qualcomm Incorporated Systems, methods, apparatus, and computer-readable media for spatially selective audio augmentation
DE102011013343A1 (en) 2011-03-08 2012-09-13 Austriamicrosystems Ag Active Noise Control System and Active Noise Reduction System
WO2012134874A1 (en) 2011-03-31 2012-10-04 Bose Corporation Adaptive feed-forward noise reduction
US20120259626A1 (en) 2011-04-08 2012-10-11 Qualcomm Incorporated Integrated psychoacoustic bass enhancement (pbe) for improved audio
US20120263317A1 (en) 2011-04-13 2012-10-18 Qualcomm Incorporated Systems, methods, apparatus, and computer readable media for equalization
US20120300960A1 (en) 2011-05-27 2012-11-29 Graeme Gordon Mackay Digital signal routing circuit
US20120300958A1 (en) 2011-05-23 2012-11-29 Bjarne Klemmensen Method of identifying a wireless communication channel in a sound system
US8325934B2 (en) 2007-12-07 2012-12-04 Board Of Trustees Of Northern Illinois University Electronic pillow for abating snoring/environmental noises, hands-free communications, and non-invasive monitoring and recording
US20120308028A1 (en) 2011-06-03 2012-12-06 Nitin Kwatra Bandlimiting anti-noise in personal audio devices having adaptive noise cancellation (anc)
US20120308021A1 (en) 2011-06-03 2012-12-06 Nitin Kwatra Speaker damage prevention in adaptive noise-canceling personal audio devices
US20120308025A1 (en) 2011-06-03 2012-12-06 Hendrix Jon D Adaptive noise canceling architecture for a personal audio device
US20120308026A1 (en) 2011-06-03 2012-12-06 Gautham Devendra Kamath Filter architecture for an adaptive noise canceler in a personal audio device
US20120308024A1 (en) 2011-06-03 2012-12-06 Jeffrey Alderson Bandlimiting anti-noise in personal audio devices having adaptive noise cancellation (anc)
US20120310640A1 (en) 2011-06-03 2012-12-06 Nitin Kwatra Mic covering detection in personal audio devices
US8379884B2 (en) 2008-01-17 2013-02-19 Funai Electric Co., Ltd. Sound signal transmitter-receiver
US8401200B2 (en) 2009-11-19 2013-03-19 Apple Inc. Electronic device and headset with speaker seal evaluation capabilities
US20130083939A1 (en) 2010-06-17 2013-04-04 Dolby Laboratories Licensing Corporation Method and apparatus for reducing the effect of environmental noise on listeners
US8442251B2 (en) 2009-04-02 2013-05-14 Oticon A/S Adaptive feedback cancellation based on inserted and/or intrinsic characteristics and matched retrieval
US20130243225A1 (en) 2007-04-19 2013-09-19 Sony Corporation Noise reduction apparatus and audio reproduction apparatus
US20130243198A1 (en) 2010-11-05 2013-09-19 Semiconductor Ideas To The Market (Itom) Method for reducing noise included in a stereo signal, stereo signal processing device and fm receiver using the method
US20130272539A1 (en) 2012-04-13 2013-10-17 Qualcomm Incorporated Systems, methods, and apparatus for spatially directive filtering
US20130287219A1 (en) 2012-04-26 2013-10-31 Cirrus Logic, Inc. Coordinated control of adaptive noise cancellation (anc) among earspeaker channels
US20130287218A1 (en) 2012-04-26 2013-10-31 Cirrus Logic, Inc. Leakage-modeling adaptive noise canceling for earspeakers
US20130301848A1 (en) 2012-05-10 2013-11-14 Cirrus Logic, Inc. Downlink tone detection and adaptation of a secondary path response model in an adaptive noise canceling system
US20130301846A1 (en) 2012-05-10 2013-11-14 Cirrus Logic, Inc. Frequency and direction-dependent ambient sound handling in personal audio devices having adaptive noise cancellation (anc)
US20130301842A1 (en) 2012-05-10 2013-11-14 Cirrus Logic, Inc. Noise burst adaptation of secondary path adaptive response in noise-canceling personal audio devices
US20130301847A1 (en) 2012-05-10 2013-11-14 Cirrus Logic, Inc. Sequenced adaptation of anti-noise generator response and secondary path response in an adaptive noise canceling system
US20130301849A1 (en) 2012-05-10 2013-11-14 Cirrus Logic, Inc. Error-signal content controlled adaptation of secondary and leakage path models in noise-canceling personal audio devices
US20130343571A1 (en) 2012-06-22 2013-12-26 Verisilicon Holdings Co., Ltd. Real-time microphone array with robust beamformer and postfilter for speech enhancement and method of operation thereof
US20140044275A1 (en) 2012-08-13 2014-02-13 Apple Inc. Active noise control with compensation for error sensing at the eardrum
US20140050332A1 (en) 2012-08-16 2014-02-20 Cisco Technology, Inc. Method and system for obtaining an audio signal
US20140072134A1 (en) 2012-09-09 2014-03-13 Apple Inc. Robust process for managing filter coefficients in adaptive noise canceling systems
US20140086425A1 (en) 2012-09-24 2014-03-27 Apple Inc. Active noise cancellation using multiple reference microphone signals
US20140177851A1 (en) 2010-06-01 2014-06-26 Sony Corporation Sound signal processing apparatus, microphone apparatus, sound signal processing method, and program
US8804974B1 (en) 2006-03-03 2014-08-12 Cirrus Logic, Inc. Ambient audio event detection in a personal audio device headset
US20140270223A1 (en) 2013-03-13 2014-09-18 Cirrus Logic, Inc. Adaptive-noise canceling (anc) effectiveness estimation and correction in a personal audio device
US20140270222A1 (en) 2013-03-14 2014-09-18 Cirrus Logic, Inc. Low-latency multi-driver adaptive noise canceling (anc) system for a personal audio device
US20140270224A1 (en) 2013-03-15 2014-09-18 Cirrus Logic, Inc. Ambient noise-based adaptation of secondary path adaptive response in noise-canceling personal audio devices
WO2015038255A1 (en) 2013-09-13 2015-03-19 Cirrus Logic, Inc. Systems and methods for adaptive noise cancellation by adaptively shaping internal white noise to train a secondary path

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2955855B1 (en) * 1998-04-24 1999-10-04 ティーオーエー株式会社 Active noise removal device
JP4252074B2 (en) * 2006-07-03 2009-04-08 ヤンマー株式会社 Signal processing method for on-line identification in active silencer
CN101763858A (en) * 2009-10-19 2010-06-30 瑞声声学科技(深圳)有限公司 Method for processing double-microphone signal

Patent Citations (220)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5410605A (en) 1991-07-05 1995-04-25 Honda Giken Kogyo Kabushiki Kaisha Active vibration control system
US5548681A (en) 1991-08-13 1996-08-20 Kabushiki Kaisha Toshiba Speech dialogue system for realizing improved communication between user and system
US5337365A (en) 1991-08-30 1994-08-09 Nissan Motor Co., Ltd. Apparatus for actively reducing noise for interior of enclosed space
US5321759A (en) 1992-04-29 1994-06-14 General Motors Corporation Active noise control system for attenuating engine generated noise
US5359662A (en) 1992-04-29 1994-10-25 General Motors Corporation Active noise control system
US5251263A (en) 1992-05-22 1993-10-05 Andrea Electronics Corporation Adaptive noise cancellation and speech enhancement system and apparatus therefor
US5278913A (en) 1992-07-28 1994-01-11 Nelson Industries, Inc. Active acoustic attenuation system with power limiting
US5445517A (en) 1992-10-14 1995-08-29 Matsushita Electric Industrial Co., Ltd. Adaptive noise silencing system of combustion apparatus
US5768124A (en) 1992-10-21 1998-06-16 Lotus Cars Limited Adaptive control system
JPH06186985A (en) 1992-12-21 1994-07-08 Nissan Motor Co Ltd Active noise controller
US5465413A (en) 1993-03-05 1995-11-07 Trimble Navigation Limited Adaptive noise cancellation
US5425105A (en) 1993-04-27 1995-06-13 Hughes Aircraft Company Multiple adaptive filter active noise canceller
US6118878A (en) 1993-06-23 2000-09-12 Noise Cancellation Technologies, Inc. Variable gain active noise canceling system with improved residual noise sensing
US7103188B1 (en) 1993-06-23 2006-09-05 Owen Jones Variable gain active noise cancelling system with improved residual noise sensing
US5586190A (en) 1994-06-23 1996-12-17 Digisonix, Inc. Active adaptive control system with weight update selective leakage
US5640450A (en) 1994-07-08 1997-06-17 Kokusai Electric Co., Ltd. Speech circuit controlling sidetone signal by background noise level
US5815582A (en) 1994-12-02 1998-09-29 Noise Cancellation Technologies, Inc. Active plus selective headset
US6041126A (en) 1995-07-24 2000-03-21 Matsushita Electric Industrial Co., Ltd. Noise cancellation system
US5699437A (en) 1995-08-29 1997-12-16 United Technologies Corporation Active noise control system using phased-array sensors
US6434246B1 (en) 1995-10-10 2002-08-13 Gn Resound As Apparatus and methods for combining audio compression and feedback cancellation in a hearing aid
US5946391A (en) 1995-11-24 1999-08-31 Nokia Mobile Phones Limited Telephones with talker sidetone
US5740256A (en) 1995-12-15 1998-04-14 U.S. Philips Corporation Adaptive noise cancelling arrangement, a noise reduction system and a transceiver
US5706344A (en) 1996-03-29 1998-01-06 Digisonix, Inc. Acoustic echo cancellation in an integrated audio and telecommunication system
US5832095A (en) 1996-10-18 1998-11-03 Carrier Corporation Noise canceling system
US5991418A (en) 1996-12-17 1999-11-23 Texas Instruments Incorporated Off-line path modeling circuitry and method for off-line feedback path modeling and off-line secondary path modeling
US6278786B1 (en) 1997-07-29 2001-08-21 Telex Communications, Inc. Active noise cancellation aircraft headset system
US20010053228A1 (en) 1997-08-18 2001-12-20 Owen Jones Noise cancellation system for active headsets
WO1999011045A1 (en) 1997-08-21 1999-03-04 The Secretary Of State For The Environment, Transport And The Regions Telephone handset noise suppression
US6219427B1 (en) 1997-11-18 2001-04-17 Gn Resound As Feedback cancellation improvements
US6282176B1 (en) 1998-03-20 2001-08-28 Cirrus Logic, Inc. Full-duplex speakerphone circuit including a supplementary echo suppressor
US6683960B1 (en) 1998-04-15 2004-01-27 Fujitsu Limited Active noise control apparatus
US6418228B1 (en) 1998-07-16 2002-07-09 Matsushita Electric Industrial Co., Ltd. Noise control system
US6434247B1 (en) 1999-07-30 2002-08-13 Gn Resound A/S Feedback cancellation apparatus and methods utilizing adaptive reference filter mechanisms
US20040120535A1 (en) 1999-09-10 2004-06-24 Starkey Laboratories, Inc. Audio signal processing
US6522746B1 (en) 1999-11-03 2003-02-18 Tellabs Operations, Inc. Synchronization of voice boundaries and their use by echo cancellers in a voice processing system
US6850617B1 (en) 1999-12-17 2005-02-01 National Semiconductor Corporation Telephone receiver circuit with dynamic sidetone signal generator controlled by voice activity detection
US20030072439A1 (en) 2000-01-27 2003-04-17 Gupta Samir K. System and method for implementation of an echo canceller
US20030185403A1 (en) 2000-03-07 2003-10-02 Alastair Sibbald Method of improving the audibility of sound from a louspeaker located close to an ear
US6766292B1 (en) 2000-03-28 2004-07-20 Tellabs Operations, Inc. Relative noise ratio weighting techniques for adaptive noise cancellation
US20020003887A1 (en) * 2000-07-05 2002-01-10 Nanyang Technological University Active noise control system with on-line secondary path modeling
US7058463B1 (en) 2000-12-29 2006-06-06 Nokia Corporation Method and apparatus for implementing a class D driver and speaker system
US6768795B2 (en) 2001-01-11 2004-07-27 Telefonaktiebolaget Lm Ericsson (Publ) Side-tone control within a telecommunication instrument
US6940982B1 (en) 2001-03-28 2005-09-06 Lsi Logic Corporation Adaptive noise cancellation (ANC) for DVD systems
US20040264706A1 (en) 2001-06-22 2004-12-30 Ray Laura R Tuned feedforward LMS filter with feedback control
US20050018862A1 (en) 2001-06-29 2005-01-27 Fisher Michael John Amiel Digital signal processing system and method for a telephony interface apparatus
WO2003015275A1 (en) 2001-08-07 2003-02-20 Dspfactory, Ltd. Sub-band adaptive signal processing in an oversampled filterbank
WO2003015074A1 (en) 2001-08-08 2003-02-20 Nanyang Technological University,Centre For Signal Processing. Active noise control system with on-line secondary path modeling
US20030063759A1 (en) 2001-08-08 2003-04-03 Brennan Robert L. Directional audio signal processing using an oversampled filterbank
US7181030B2 (en) 2002-01-12 2007-02-20 Oticon A/S Wind noise insensitive hearing aid
US20090175466A1 (en) 2002-02-05 2009-07-09 Mh Acoustics, Llc Noise-reducing directional microphone array
US20130010982A1 (en) 2002-02-05 2013-01-10 Mh Acoustics,Llc Noise-reducing directional microphone array
WO2004009007A1 (en) 2002-07-19 2004-01-29 The Penn State Research Foundation A linear independent method for noninvasive online secondary path modeling
WO2004017303A1 (en) 2002-08-16 2004-02-26 Dspfactory Ltd. Method and system for processing subband signals using adaptive filters
US20040047464A1 (en) 2002-09-11 2004-03-11 Zhuliang Yu Adaptive noise cancelling microphone system
US20040167777A1 (en) 2003-02-21 2004-08-26 Hetherington Phillip A. System for suppressing wind noise
US20040165736A1 (en) 2003-02-21 2004-08-26 Phil Hetherington Method and apparatus for suppressing wind noise
US20050004796A1 (en) 2003-02-27 2005-01-06 Telefonaktiebolaget Lm Ericsson (Publ), Audibility enhancement
US20040202333A1 (en) 2003-04-08 2004-10-14 Csermak Brian D. Hearing instrument with self-diagnostics
US20070053524A1 (en) 2003-05-09 2007-03-08 Tim Haulick Method and system for communication enhancement in a noisy environment
GB2401744A (en) 2003-05-14 2004-11-17 Ultra Electronics Ltd An adaptive noise control unit with feedback compensation
US20040240677A1 (en) 2003-05-29 2004-12-02 Masahide Onishi Active noise control system
US20040242160A1 (en) 2003-05-30 2004-12-02 Nokia Corporation Mobile phone for voice adaptation in socially sensitive environment
US20050117754A1 (en) 2003-12-02 2005-06-02 Atsushi Sakawaki Active noise cancellation helmet, motor vehicle system including the active noise cancellation helmet, and method of canceling noise in helmet
US20050207585A1 (en) 2004-03-17 2005-09-22 Markus Christoph Active noise tuning system
US20050240401A1 (en) 2004-04-23 2005-10-27 Acoustic Technologies, Inc. Noise suppression based on Bark band weiner filtering and modified doblinger noise estimate
US20060035593A1 (en) 2004-08-12 2006-02-16 Motorola, Inc. Noise and interference reduction in digitized signals
US20070258597A1 (en) 2004-08-24 2007-11-08 Oticon A/S Low Frequency Phase Matching for Microphones
EP1880699A2 (en) 2004-08-25 2008-01-23 Phonak AG Method for manufacturing an earplug
US20060055910A1 (en) 2004-08-27 2006-03-16 Jong-Haw Lee Exposure apparatus adapted to detect abnormal operating phenomenon
US20060069556A1 (en) 2004-09-15 2006-03-30 Nadjar Hamid S Method and system for active noise cancellation
US20060153400A1 (en) 2005-01-12 2006-07-13 Yamaha Corporation Microphone and sound amplification system
US7680456B2 (en) 2005-02-16 2010-03-16 Texas Instruments Incorporated Methods and apparatus to perform signal removal in a low intermediate frequency receiver
US7330739B2 (en) 2005-03-31 2008-02-12 Nxp B.V. Method and apparatus for providing a sidetone in a wireless communication device
US20080226098A1 (en) 2005-04-29 2008-09-18 Tim Haulick Detection and suppression of wind noise in microphone signals
US20070033029A1 (en) 2005-05-26 2007-02-08 Yamaha Hatsudoki Kabushiki Kaisha Noise cancellation helmet, motor vehicle system including the noise cancellation helmet, and method of canceling noise in helmet
US20100207317A1 (en) 2005-06-14 2010-08-19 Glory, Ltd. Paper-sheet feeding device with kicker roller
WO2007007916A1 (en) 2005-07-14 2007-01-18 Matsushita Electric Industrial Co., Ltd. Transmitting apparatus and method capable of generating a warning depending on sound types
US20070030989A1 (en) 2005-08-02 2007-02-08 Gn Resound A/S Hearing aid with suppression of wind noise
US20070038441A1 (en) 2005-08-09 2007-02-15 Honda Motor Co., Ltd. Active noise control system
US20100284546A1 (en) 2005-08-18 2010-11-11 Debrunner Victor Active noise control algorithm that requires no secondary path identification based on the SPR property
US20070047742A1 (en) 2005-08-26 2007-03-01 Step Communications Corporation, A Nevada Corporation Method and system for enhancing regional sensitivity noise discrimination
US20100158330A1 (en) 2005-09-12 2010-06-24 Dvp Technologies Ltd. Medical Image Processing
US20070076896A1 (en) 2005-09-28 2007-04-05 Kabushiki Kaisha Toshiba Active noise-reduction control apparatus and method
US20100150367A1 (en) 2005-10-21 2010-06-17 Ko Mizuno Noise control device
US20070154031A1 (en) 2006-01-05 2007-07-05 Audience, Inc. System and method for utilizing inter-microphone level differences for speech enhancement
US20080019548A1 (en) 2006-01-30 2008-01-24 Audience, Inc. System and method for utilizing omni-directional microphones for speech enhancement
US8804974B1 (en) 2006-03-03 2014-08-12 Cirrus Logic, Inc. Ambient audio event detection in a personal audio device headset
WO2007113487A1 (en) 2006-04-01 2007-10-11 Wolfson Microelectronics Plc Ambient noise-reduction control system
US20090034748A1 (en) * 2006-04-01 2009-02-05 Alastair Sibbald Ambient noise-reduction control system
US20090046867A1 (en) 2006-04-12 2009-02-19 Wolfson Microelectronics Plc Digtal Circuit Arrangements for Ambient Noise-Reduction
US20110144984A1 (en) 2006-05-11 2011-06-16 Alon Konchitsky Voice coder with two microphone system and strategic microphone placement to deter obstruction for a digital communication device
US7742790B2 (en) 2006-05-23 2010-06-22 Alon Konchitsky Environmental noise reduction and cancellation for a communication device including for a wireless and cellular telephone
US20070297620A1 (en) 2006-06-27 2007-12-27 Choy Daniel S J Methods and Systems for Producing a Zone of Reduced Background Noise
US20080101589A1 (en) 2006-10-31 2008-05-01 Palm, Inc. Audio output using multiple speakers
US20080107281A1 (en) 2006-11-02 2008-05-08 Masahito Togami Acoustic echo canceller system
US20080144853A1 (en) 2006-12-06 2008-06-19 Sommerfeldt Scott D Secondary Path Modeling for Active Noise Control
US8019050B2 (en) 2007-01-03 2011-09-13 Motorola Solutions, Inc. Method and apparatus for providing feedback of vocal quality to a user
EP1947642A1 (en) 2007-01-16 2008-07-23 Harman/Becker Automotive Systems GmbH Active noise control system
US20080181422A1 (en) * 2007-01-16 2008-07-31 Markus Christoph Active noise control system
US20080177532A1 (en) 2007-01-22 2008-07-24 D.S.P. Group Ltd. Apparatus and methods for enhancement of speech
US20100061564A1 (en) 2007-02-07 2010-03-11 Richard Clemow Ambient noise reduction system
US20100166203A1 (en) 2007-03-19 2010-07-01 Sennheiser Electronic Gmbh & Co. Kg Headset
US7365669B1 (en) 2007-03-28 2008-04-29 Cirrus Logic, Inc. Low-delay signal processing based on highly oversampled digital processing
US20080240457A1 (en) 2007-03-30 2008-10-02 Honda Motor Co., Ltd. Active noise control apparatus
US20080240455A1 (en) 2007-03-30 2008-10-02 Honda Motor Co., Ltd. Active noise control apparatus
US20080240413A1 (en) 2007-04-02 2008-10-02 Microsoft Corporation Cross-correlation based echo canceller controllers
US20130243225A1 (en) 2007-04-19 2013-09-19 Sony Corporation Noise reduction apparatus and audio reproduction apparatus
US20090012783A1 (en) 2007-07-06 2009-01-08 Audience, Inc. System and method for adaptive intelligent noise suppression
US7817808B2 (en) 2007-07-19 2010-10-19 Alon Konchitsky Dual adaptive structure for speech enhancement
US20090041260A1 (en) 2007-08-10 2009-02-12 Oticon A/S Active noise cancellation in hearing devices
US20090060222A1 (en) 2007-09-05 2009-03-05 Samsung Electronics Co., Ltd. Sound zoom method, medium, and apparatus
US20090080670A1 (en) 2007-09-24 2009-03-26 Sound Innovations Inc. In-Ear Digital Electronic Noise Cancelling and Communication Device
US20090086990A1 (en) 2007-09-27 2009-04-02 Markus Christoph Active noise control using bass management
US8325934B2 (en) 2007-12-07 2012-12-04 Board Of Trustees Of Northern Illinois University Electronic pillow for abating snoring/environmental noises, hands-free communications, and non-invasive monitoring and recording
GB2455824A (en) 2007-12-21 2009-06-24 Wolfson Microelectronics Plc Active noise cancellation system turns off or lessens cancellation during voiceless intervals
GB2455821A (en) 2007-12-21 2009-06-24 Wolfson Microelectronics Plc Active noise cancellation system with split digital filter
US20100266137A1 (en) 2007-12-21 2010-10-21 Alastair Sibbald Noise cancellation system with gain control based on noise level
GB2455828A (en) 2007-12-21 2009-06-24 Wolfson Microelectronics Plc Noise cancellation system with adaptive filter and two different sample rates
US20100310086A1 (en) 2007-12-21 2010-12-09 Anthony James Magrath Noise cancellation system with lower rate emulation
US8379884B2 (en) 2008-01-17 2013-02-19 Funai Electric Co., Ltd. Sound signal transmitter-receiver
US20100291891A1 (en) 2008-01-25 2010-11-18 Nxp B.V. Improvements in or relating to radio receivers
US20090196429A1 (en) 2008-01-31 2009-08-06 Qualcomm Incorporated Signaling microphone covering to the user
US20090220107A1 (en) 2008-02-29 2009-09-03 Audience, Inc. System and method for providing single microphone noise suppression fallback
US20090238369A1 (en) 2008-03-18 2009-09-24 Qualcomm Incorporated Systems and methods for detecting wind noise using multiple audio sources
US20090245529A1 (en) 2008-03-28 2009-10-01 Sony Corporation Headphone device, signal processing device, and signal processing method
US20090254340A1 (en) 2008-04-07 2009-10-08 Cambridge Silicon Radio Limited Noise Reduction
US20090290718A1 (en) 2008-05-21 2009-11-26 Philippe Kahn Method and Apparatus for Adjusting Audio for a User Environment
US20090296965A1 (en) 2008-05-27 2009-12-03 Mariko Kojima Hearing aid, and hearing-aid processing method and integrated circuit for hearing aid
US20090304200A1 (en) 2008-06-09 2009-12-10 Samsung Electronics Co., Ltd. Adaptive mode control apparatus and method for adaptive beamforming based on detection of user direction sound
US20090311979A1 (en) 2008-06-12 2009-12-17 Atheros Communications, Inc. Polar modulator with path delay compensation
US20100014685A1 (en) 2008-06-13 2010-01-21 Michael Wurm Adaptive noise control system
EP2133866A1 (en) 2008-06-13 2009-12-16 Harman Becker Automotive Systems GmbH Adaptive noise control system
US20110130176A1 (en) 2008-06-27 2011-06-02 Anthony James Magrath Noise cancellation system
US20110106533A1 (en) 2008-06-30 2011-05-05 Dolby Laboratories Licensing Corporation Multi-Microphone Voice Activity Detector
US20100014683A1 (en) 2008-07-15 2010-01-21 Panasonic Corporation Noise reduction device
US20110142247A1 (en) 2008-07-29 2011-06-16 Dolby Laboratories Licensing Corporation MMethod for Adaptive Control and Equalization of Electroacoustic Channels
US20100069114A1 (en) 2008-09-15 2010-03-18 Lee Michael M Sidetone selection for headsets or earphones
US8290537B2 (en) 2008-09-15 2012-10-16 Apple Inc. Sidetone adjustment based on headset or earphone type
US20100142715A1 (en) 2008-09-16 2010-06-10 Personics Holdings Inc. Sound Library and Method
US20100082339A1 (en) 2008-09-30 2010-04-01 Alon Konchitsky Wind Noise Reduction
US20100098263A1 (en) 2008-10-20 2010-04-22 Pan Davis Y Active noise reduction adaptive filter leakage adjusting
US20100098265A1 (en) 2008-10-20 2010-04-22 Pan Davis Y Active noise reduction adaptive filter adaptation rate adjusting
US20100124337A1 (en) 2008-11-20 2010-05-20 Harman International Industries, Incorporated Quiet zone control system
US20100124336A1 (en) 2008-11-20 2010-05-20 Harman International Industries, Incorporated System for active noise control with audio signal compensation
US20100131269A1 (en) 2008-11-24 2010-05-27 Qualcomm Incorporated Systems, methods, apparatus, and computer program products for enhanced active noise cancellation
US20110249826A1 (en) 2008-12-18 2011-10-13 Koninklijke Philips Electronics N.V. Active audio noise cancelling
US20100195844A1 (en) 2009-01-30 2010-08-05 Markus Christoph Adaptive noise control system
EP2216774A1 (en) 2009-01-30 2010-08-11 Harman Becker Automotive Systems GmbH Adaptive noise control system
US20100195838A1 (en) 2009-02-03 2010-08-05 Nokia Corporation Apparatus including microphone arrangements
US20130343556A1 (en) 2009-02-03 2013-12-26 Nokia Corporation Apparatus Including Microphone Arrangements
WO2010117714A1 (en) 2009-03-30 2010-10-14 Bose Corporation Personal acoustic device position determination
US20100246855A1 (en) 2009-03-31 2010-09-30 Apple Inc. Dynamic audio parameter adjustment using touch sensing
US8442251B2 (en) 2009-04-02 2013-05-14 Oticon A/S Adaptive feedback cancellation based on inserted and/or intrinsic characteristics and matched retrieval
EP2237573A1 (en) 2009-04-02 2010-10-06 Oticon A/S Adaptive feedback cancellation method and apparatus therefor
US20100296668A1 (en) 2009-04-23 2010-11-25 Qualcomm Incorporated Systems, methods, apparatus, and computer-readable media for automatic control of active noise cancellation
US8249262B2 (en) 2009-04-27 2012-08-21 Siemens Medical Instruments Pte. Ltd. Device for acoustically analyzing a hearing device and analysis method
US20100272283A1 (en) 2009-04-28 2010-10-28 Carreras Ricardo F Digital high frequency phase compensation
US20100274564A1 (en) 2009-04-28 2010-10-28 Pericles Nicholas Bakalos Coordinated anr reference sound compression
US20100272276A1 (en) 2009-04-28 2010-10-28 Carreras Ricardo F ANR Signal Processing Topology
US20100296666A1 (en) 2009-05-25 2010-11-25 National Chin-Yi University Of Technology Apparatus and method for noise cancellation in voice communication
US20100322430A1 (en) 2009-06-17 2010-12-23 Sony Ericsson Mobile Communications Ab Portable communication device and a method of processing signals therein
US20110007907A1 (en) 2009-07-10 2011-01-13 Qualcomm Incorporated Systems, methods, apparatus, and computer-readable media for adaptive active noise cancellation
US20110129098A1 (en) 2009-10-28 2011-06-02 Delano Cary L Active noise cancellation
US8401200B2 (en) 2009-11-19 2013-03-19 Apple Inc. Electronic device and headset with speaker seal evaluation capabilities
US20110158419A1 (en) 2009-12-30 2011-06-30 Lalin Theverapperuma Adaptive digital noise canceller
US20110206214A1 (en) 2010-02-25 2011-08-25 Markus Christoph Active noise reduction system
US20110222698A1 (en) 2010-03-12 2011-09-15 Panasonic Corporation Noise reduction device
US20110288860A1 (en) 2010-05-20 2011-11-24 Qualcomm Incorporated Systems, methods, apparatus, and computer-readable media for processing of speech signals using head-mounted microphone pair
US20140177851A1 (en) 2010-06-01 2014-06-26 Sony Corporation Sound signal processing apparatus, microphone apparatus, sound signal processing method, and program
US20110293103A1 (en) 2010-06-01 2011-12-01 Qualcomm Incorporated Systems, methods, devices, apparatus, and computer program products for audio equalization
US20120140917A1 (en) 2010-06-04 2012-06-07 Apple Inc. Active noise cancellation decisions using a degraded reference
US20110299695A1 (en) 2010-06-04 2011-12-08 Apple Inc. Active noise cancellation decisions in a portable audio device
US20120148062A1 (en) 2010-06-11 2012-06-14 Nxp B.V. Audio device
EP2395500A1 (en) 2010-06-11 2011-12-14 Nxp B.V. Audio device
EP2395501A1 (en) 2010-06-14 2011-12-14 Harman Becker Automotive Systems GmbH Adaptive noise control
US20110305347A1 (en) 2010-06-14 2011-12-15 Michael Wurm Adaptive noise control
US20130083939A1 (en) 2010-06-17 2013-04-04 Dolby Laboratories Licensing Corporation Method and apparatus for reducing the effect of environmental noise on listeners
US20110317848A1 (en) 2010-06-23 2011-12-29 Motorola, Inc. Microphone Interference Detection Method and Apparatus
GB2484722A (en) 2010-10-21 2012-04-25 Wolfson Microelectronics Plc Control of a noise cancellation system according to a detected position of an audio device
US20130243198A1 (en) 2010-11-05 2013-09-19 Semiconductor Ideas To The Market (Itom) Method for reducing noise included in a stereo signal, stereo signal processing device and fm receiver using the method
US20120135787A1 (en) 2010-11-25 2012-05-31 Kyocera Corporation Mobile phone and echo reduction method therefore
US20120140942A1 (en) 2010-12-01 2012-06-07 Dialog Semiconductor Gmbh Reduced delay digital active noise cancellation
US20150092953A1 (en) 2010-12-03 2015-04-02 Cirrus Logic, Inc. Ear-coupling detection and adjustment of adaptive response in noise-canceling in personal audio devices
US20120207317A1 (en) 2010-12-03 2012-08-16 Ali Abdollahzadeh Milani Ear-coupling detection and adjustment of adaptive response in noise-canceling in personal audio devices
US8908877B2 (en) 2010-12-03 2014-12-09 Cirrus Logic, Inc. Ear-coupling detection and adjustment of adaptive response in noise-canceling in personal audio devices
US20120140943A1 (en) 2010-12-03 2012-06-07 Hendrix Jon D Oversight control of an adaptive noise canceler in a personal audio device
US20120155666A1 (en) 2010-12-16 2012-06-21 Nair Vijayakumaran V Adaptive noise cancellation
US20120170766A1 (en) 2011-01-05 2012-07-05 Cambridge Silicon Radio Limited ANC For BT Headphones
US20120215519A1 (en) 2011-02-23 2012-08-23 Qualcomm Incorporated Systems, methods, apparatus, and computer-readable media for spatially selective audio augmentation
DE102011013343A1 (en) 2011-03-08 2012-09-13 Austriamicrosystems Ag Active Noise Control System and Active Noise Reduction System
US20120250873A1 (en) 2011-03-31 2012-10-04 Bose Corporation Adaptive feed-forward noise reduction
WO2012134874A1 (en) 2011-03-31 2012-10-04 Bose Corporation Adaptive feed-forward noise reduction
US20120259626A1 (en) 2011-04-08 2012-10-11 Qualcomm Incorporated Integrated psychoacoustic bass enhancement (pbe) for improved audio
US20120263317A1 (en) 2011-04-13 2012-10-18 Qualcomm Incorporated Systems, methods, apparatus, and computer readable media for equalization
US20120300958A1 (en) 2011-05-23 2012-11-29 Bjarne Klemmensen Method of identifying a wireless communication channel in a sound system
US20120300960A1 (en) 2011-05-27 2012-11-29 Graeme Gordon Mackay Digital signal routing circuit
US20120308024A1 (en) 2011-06-03 2012-12-06 Jeffrey Alderson Bandlimiting anti-noise in personal audio devices having adaptive noise cancellation (anc)
US20120308021A1 (en) 2011-06-03 2012-12-06 Nitin Kwatra Speaker damage prevention in adaptive noise-canceling personal audio devices
US20120308028A1 (en) 2011-06-03 2012-12-06 Nitin Kwatra Bandlimiting anti-noise in personal audio devices having adaptive noise cancellation (anc)
US20140211953A1 (en) 2011-06-03 2014-07-31 Cirrus Logic, Inc. Bandlimiting anti-noise in personal audio devices having adaptive noise cancellation (anc)
US20120308026A1 (en) 2011-06-03 2012-12-06 Gautham Devendra Kamath Filter architecture for an adaptive noise canceler in a personal audio device
US20120308025A1 (en) 2011-06-03 2012-12-06 Hendrix Jon D Adaptive noise canceling architecture for a personal audio device
US20120310640A1 (en) 2011-06-03 2012-12-06 Nitin Kwatra Mic covering detection in personal audio devices
US20130272539A1 (en) 2012-04-13 2013-10-17 Qualcomm Incorporated Systems, methods, and apparatus for spatially directive filtering
US20130287219A1 (en) 2012-04-26 2013-10-31 Cirrus Logic, Inc. Coordinated control of adaptive noise cancellation (anc) among earspeaker channels
US20130287218A1 (en) 2012-04-26 2013-10-31 Cirrus Logic, Inc. Leakage-modeling adaptive noise canceling for earspeakers
US20130301848A1 (en) 2012-05-10 2013-11-14 Cirrus Logic, Inc. Downlink tone detection and adaptation of a secondary path response model in an adaptive noise canceling system
US20130301847A1 (en) 2012-05-10 2013-11-14 Cirrus Logic, Inc. Sequenced adaptation of anti-noise generator response and secondary path response in an adaptive noise canceling system
US20130301842A1 (en) 2012-05-10 2013-11-14 Cirrus Logic, Inc. Noise burst adaptation of secondary path adaptive response in noise-canceling personal audio devices
US20130301846A1 (en) 2012-05-10 2013-11-14 Cirrus Logic, Inc. Frequency and direction-dependent ambient sound handling in personal audio devices having adaptive noise cancellation (anc)
US20130301849A1 (en) 2012-05-10 2013-11-14 Cirrus Logic, Inc. Error-signal content controlled adaptation of secondary and leakage path models in noise-canceling personal audio devices
US20130343571A1 (en) 2012-06-22 2013-12-26 Verisilicon Holdings Co., Ltd. Real-time microphone array with robust beamformer and postfilter for speech enhancement and method of operation thereof
US20140044275A1 (en) 2012-08-13 2014-02-13 Apple Inc. Active noise control with compensation for error sensing at the eardrum
US20140050332A1 (en) 2012-08-16 2014-02-20 Cisco Technology, Inc. Method and system for obtaining an audio signal
US20140072134A1 (en) 2012-09-09 2014-03-13 Apple Inc. Robust process for managing filter coefficients in adaptive noise canceling systems
US20140086425A1 (en) 2012-09-24 2014-03-27 Apple Inc. Active noise cancellation using multiple reference microphone signals
US20140270223A1 (en) 2013-03-13 2014-09-18 Cirrus Logic, Inc. Adaptive-noise canceling (anc) effectiveness estimation and correction in a personal audio device
US20140270222A1 (en) 2013-03-14 2014-09-18 Cirrus Logic, Inc. Low-latency multi-driver adaptive noise canceling (anc) system for a personal audio device
US20140270224A1 (en) 2013-03-15 2014-09-18 Cirrus Logic, Inc. Ambient noise-based adaptation of secondary path adaptive response in noise-canceling personal audio devices
WO2015038255A1 (en) 2013-09-13 2015-03-19 Cirrus Logic, Inc. Systems and methods for adaptive noise cancellation by adaptively shaping internal white noise to train a secondary path

Non-Patent Citations (73)

* Cited by examiner, † Cited by third party
Title
Abdollahzadeh Milani, et al., "On Maximum Achievable Noise Reduction in ANC Systems",2010 IEEE International Conference on Acoustics Speech and Signal Processing, Mar. 14-19, 2010, pp. 349-352, Dallas, TX, US.
Akhtar, et al., "A Method for Online Secondary Path Modeling in Active Noise Control Systems," IEEE International Symposium on Circuits and Systems, May 23-26, 2005, pp. 264-267, vol. 1, Kobe, Japan.
Black, John W., "An Application of Side-Tone in Subjective Tests of Microphones and Headsets", Project Report No. NM 001 064.01.20, Research Report of the U.S. Naval School of Aviation Medicine, Feb. 1, 1954, 12 pages (pp. 1-12 in pdf), Pensacola, FL, US.
Booij, et al., "Virtual sensors for local, three dimensional, broadband multiple-channel active noise control and the effects on the quiet zones", Proceedings of the International Conference on Noise and Vibration Engineering, ISMA 2010, Sep. 20-22, 2010, pp. 151-166, Leuven.
Campbell, Mikey, "Apple looking into self-adjusting earbud headphones with noise cancellation tech", Apple Insider, Jul. 4, 2013, pp. 1-10 (10 pages in pdf), downloaded on May 14, 2014 from http://appleinsider.com/articles/13/07/04/apple-looking-into-self-adjusting-earbud-headphones-with-noise-cancellation-tech.
Cohen, et al., "Noise Estimation by Minima Controlled Recursive Averaging for Robust Speech Enhancement", IEEE Signal Processing Letters, Jan. 2002, pp. 12-15, vol. 9, No. 1, Piscataway, NJ, US.
Cohen, Israel, "Noise Spectrum Estimation in Adverse Environments: Improved Minima Controlled Recursive Averaging", IEEE Transactions on Speech and Audio Processing, Sep. 2003, pp. 1-11, vol. 11, Issue 5, Piscataway, NJ, US.
Davari, et al., "A New Online Secondary Path Modeling Method for Feedforward Active Noise Control Systems," IEEE International Conference on Industrial Technology, Apr. 21-24, 2008, pp. 1-6, Chengdu, China.
Erkelens, et al., "Tracking of Nonstationary Noise Based on Data-Driven Recursive Noise Power Estimation", IEEE Transactions on Audio Speech and Language Processing, Aug. 2008, pp. 1112-1123, vol. 16, No. 6, Piscataway, NJ, US.
Feng, et al.., "A broadband self-tuning active noise equaliser", Signal Processing, Oct. 1, 1997, pp. 251-256, vol. 62, No. 2, Elsevier Science Publishers B.V. Amsterdam, NL.
Gao, et al., "Adaptive Linearization of a Loudspeaker," IEEE International Conference on Acoustics, Speech, and Signal Processing, Apr. 14-17, 1991, pp. 3589-3592, Toronto, Ontario, CA.
Hurst, et al., "An improved double sampling scheme for switched-capacitor delta-sigma modulators", 1992 IEEE Int. Symp. on Circuits and Systems, May 10-13, 1992, vol. 3, pp. 1179-1182, San Diego, CA.
International Preliminary Report on Patentability in PCT/US2012/039336, mailed on Jan. 10, 2014, 24 pages (pp. 1-24 in pdf).
International Search Report and Written Opinion in PCT/US2012/039336, mailed on Apr. 12, 2013, 14 pages (pp. 1-14 in pdf).
Jin, et al. "A simultaneous equation method-based online secondary path modeling algorithm for active noise control", Journal of Sound and Vibration, Apr. 25, 2007, pp. 455-474, vol. 303, No. 3-5, London, GB.
Johns, et al., "Continuous-Time LMS Adaptive Recursive Filters," IEEE Transactions on Circuits and Systems, Jul. 1991, pp. 769-778, vol. 38, No. 7, IEEE Press, Piscataway, NJ.
Kates, James M., "Principles of Digital Dynamic Range Compression," Trends in Amplification, Spring 2005, pp. 45-76, vol. 9, No. 2, Sage Publications.
Kuo, et al., "Active Noise Control: A Tutorial Review," Proceedings of the IEEE, Jun. 1999, pp. 943-973, vol. 87, No. 6, IEEE Press, Piscataway, NJ.
Kuo, et al., "Residual noise shaping technique for active noise control systems", J. Acoust. Soc. Am. 95 (3), Mar. 1994, pp. 1665-1668.
Lan, et al., "An Active Noise Control System Using Online Secondary Path Modeling With Reduced Auxiliary Noise," IEEE Signal Processing Letters, Jan. 2002, pp. 16-18, vol. 9, Issue 1, IEEE Press, Piscataway, NJ.
Lane, et al., "Voice Level: Autophonic Scale, Perceived Loudness, and the Effects of Sidetone", The Journal of the Acoustical Society of America, Feb. 1961, pp. 160-167, vol. 33, No. 2., Cambridge, MA, US.
Liu, et al., "Analysis of Online Secondary Path Modeling With Auxiliary Noise Scaled by Residual Noise Signal," IEEE Transactions on Audio, Speech and Language Processing, Nov. 2010, pp. 1978-1993, vol. 18, Issue 8, IEEE Press, Piscataway, NJ.
Liu, et al., "Compensatory Responses to Loudness-shifted Voice Feedback During Production of Mandarin Speech", Journal of the Acoustical Society of America, Oct. 2007, pp. 2405-2412, vol. 122, No. 4.
Lopez-Caudana, Edgar Omar, "Active Noise Cancellation: The Unwanted Signal and The Hybrid Solution", Adaptive Filtering Applications, Dr. Lino Garcia (Ed.), Jul. 2011, pp. 49-84, ISBN: 978-953-307-306-4, InTech.
Lopez-Gaudana, et al., "A hybrid active noise cancelling with secondary path modeling", 51st Midwest Symposium on Circuits and Systems, MWSCAS 2008, Aug. 10-13, 2008, pp. 277-280, IEEE, Knoxville, TN.
Mali, Dilip, "Comparison of DC Offset Effects on LMS Algorithm and its Derivatives," International Journal of Recent Trends in Engineering, May 2009, pp. 323-328, vol. 1, No. 1, Academy Publisher.
Martin, Rainer, "Noise Power Spectral Density Estimation Based on Optimal Smoothing and Minimum Statistics", IEEE Transactions on Speech and Audio Processing, Jul. 2001, pp. 504-512, vol. 9, No. 5, Piscataway, NJ, US.
Martin, Rainer, "Spectral Subtraction Based on Minimum Statistics", Signal Processing VII Theories and Applications, Proceedings of EUSIPCO-94, 7th European Signal Processing Conference, Sep. 13-16, 1994, pp. 1182-1185, vol. III, Edinburgh, Scotland, U.K.
Morgan, et al., A Delayless Subband Adaptive Filter Architecture, IEEE Transactions on Signal Processing, IEEE Service Center, Aug. 1995, pp. 1819-1829, vol. 43, No. 8, New York, NY, US.
Paepcke, et al., "Yelling in the Hall: Using Sidetone to Address a Problem with Mobile Remote Presence Systems", Symposium on User Interface Software and Technology, Oct. 16-19, 2011, 10 pages (pp. 1-10 in pdf), Santa Barbara, CA, US.
Parkins, et al., "Narrowband and broadband active control in an enclosure using the acoustic energy density", J. Acoust. Soc. Am. Jul. 2000, pp. 192-203, vol. 108, issue 1, US.
Peters, Robert W., "The Effect of High-Pass and Low-Pass Filtering of Side-Tone Upon Speaker Intelligibility", Project Report No. NM 001 064.01.25, Research Report of the U.S. Naval School of Aviation Medicine, Aug. 16, 1954, 13 pages (pp. 1-13 in pdf), Pensacola, FL, US.
Pfann, et al., "LMS Adaptive Filtering with Delta-Sigma Modulated Input Signals," IEEE Signal Processing Letters, Apr. 1998, pp. 95-97, vol. 5, No. 4, IEEE Press, Piscataway, NJ.
Rangachari, et al., "A noise-estimation algorithm for highly non-stationary environments", Speech Communication, Feb. 2006, pp. 220-231, vol. 48, No. 2. Elsevier Science Publishers.
Rao, et al., "A Novel Two State Single Channel Speech Enhancement Technique", India Conference (INDICON) 2011 Annual IEEE, IEEE, Dec. 2011, 6 pages (pp. 1-6 in pdf), Piscataway, NJ, US.
Ryan, et al., "Optimum Near-Field Performance of Microphone Arrays Subject to a Far-Field Beampattern Constraint", J. Acoust. Soc. Am., Nov. 2000, pp. 2248-2255, 108 (5), Pt. 1, Ottawa, Ontario, Canada.
Senderowicz, et al., "Low-Voltage Double-Sampled Delta-Sigma Converters", IEEE Journal on Solid-State Circuits, Dec. 1997, pp. 1907-1919, vol. 32, No. 12, Piscataway, NJ.
Shoval, et al., "Comparison of DC Offset Effects in Four LMS Adaptive Algorithms," IEEE Transactions on Circuits and Systems II: Analog and Digital Processing, Mar. 1995, pp. 176-185, vol. 42, Issue 3, IEEE Press, Piscataway, NJ.
Silva, et al., "Convex Combination of Adaptive Filters With Different Tracking Capabilities," IEEE International Conference on Acoustics, Speech, and Signal Processing, Apr. 15-20, 2007, pp. III 925-928, vol. 3, Honolulu, HI, USA.
Therrien, et al., "Sensory Attenuation of Self-Produced Feedback: The Lombard Effect Revisited", PLOS ONE, Nov. 2012, pp. 1-7, vol. 7, Issue 11, e49370, Ontario, Canada.
Toochinda, et al. "A Single-Input Two-Output Feedback Formulation for ANC Problems," Proceedings of the 2001 American Control Conference, Jun. 2001, pp. 923-928, vol. 2, Arlington, VA.
U.S. Appl. No. 13/686,353, filed Nov. 27, 2012, Hendrix, et al.
U.S. Appl. No. 13/692,367, filed Dec. 3, 2012, Alderson, et al.
U.S. Appl. No. 13/721,832, filed Dec. 20, 2012, Lu, et al.
U.S. Appl. No. 13/722,119, filed Dec. 20, 2012, Hendrix, et al.
U.S. Appl. No. 13/724,656, filed Dec. 21, 2012, Lu, et al.
U.S. Appl. No. 13/727,718, filed Dec. 27, 2012, Alderson, et al.
U.S. Appl. No. 13/729,141, filed Dec. 28, 2012, Zhou, et al.
U.S. Appl. No. 13/762,504, filed Feb. 8, 2013, Abdollahzadeh Milani, et al.
U.S. Appl. No. 13/784,018, filed Mar. 4, 2013, Alderson, et al.
U.S. Appl. No. 13/787,906, filed Mar. 7, 2013, Alderson, et al.
U.S. Appl. No. 13/794,931, filed Mar. 12, 2013, Lu, et al.
U.S. Appl. No. 13/794,979, filed Mar. 12, 2013, Alderson, et al.
U.S. Appl. No. 13/795,160, filed Mar. 12, 2013, Hendrix, et al.
U.S. Appl. No. 13/896,526, filed May 17, 2013, Naderi.
U.S. Appl. No. 13/924,935, filed Jun. 24, 2013, Hellman.
U.S. Appl. No. 13/968,007, filed Aug. 15, 2013, Hendrix, et al.
U.S. Appl. No. 13/968,013, filed Aug. 15, 2013, Abdollahzadeh Milani, et al.
U.S. Appl. No. 14/029,159, filed Sep. 17, 2013, Li, et al.
U.S. Appl. No. 14/062,951, filed Oct. 25, 2013, Zhou, et al.
U.S. Appl. No. 14/101,777, filed Dec. 10, 2013, Alderson et al.
U.S. Appl. No. 14/101,955, filed Dec. 10, 2013, Alderson.
U.S. Appl. No. 14/197,814, filed Mar. 5, 2014, Kaller, et al.
U.S. Appl. No. 14/210,537, filed Mar. 14, 2014, Abdollahzadeh Milani, et al.
U.S. Appl. No. 14/210,589, filed Mar. 14, 2014, Abdollahzadeh Milani, et al.
U.S. Appl. No. 14/228,322, filed Mar. 28, 2014, Alderson, et al.
U.S. Appl. No. 14/252,235, filed Apr. 14, 2014, Lu, et al.
U.S. Appl. No. 14/578,567, filed Dec. 22, 2014, Kwatra, et al.
U.S. Appl. No. 14/656,124, filed Mar. 12, 2015, Hendrix, et al.
U.S. Appl. No. 14/734,321, filed Jun. 9, 2015, Alderson, et al.
Widrow, B., et al., Adaptive Noise Cancelling; Principles and Applications, Proceedings of the IEEE, Dec. 1975, pp. 1692-1716, vol. 63, No. 13, IEEE, New York, NY, US.
Written Opinion of the International Preliminary Examining Authority in PCT/US2012/039336, mailed on Sep. 24, 2013, 5 pages (pp. 1-5 in pdf).
Zhang, et al., "A Robust Online Secondary Path Modeling Method with Auxiliary Noise Power Scheduling Strategy and Norm Constraint Manipulation", IEEE Transactions on Speech and Audio Processing, IEEE Service Center, Jan. 1, 2003, pp. 45-53, vol. 11, No. 1, NY.

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10249284B2 (en) 2011-06-03 2019-04-02 Cirrus Logic, Inc. Bandlimiting anti-noise in personal audio devices having adaptive noise cancellation (ANC)
US20150271602A1 (en) * 2012-11-02 2015-09-24 Bose Corporation Binaural Telepresence
US9628914B2 (en) * 2012-11-02 2017-04-18 Bose Corporation Binaural telepresence

Also Published As

Publication number Publication date
EP2715716A2 (en) 2014-04-09
CN103718238B (en) 2016-03-23
JP2014521989A (en) 2014-08-28
KR101918466B1 (en) 2018-11-15
US20120308027A1 (en) 2012-12-06
EP2715716B1 (en) 2016-05-11
WO2012166511A2 (en) 2012-12-06
JP6106164B2 (en) 2017-03-29
CN103718238A (en) 2014-04-09
KR20140035446A (en) 2014-03-21
WO2012166511A3 (en) 2013-06-06

Similar Documents

Publication Publication Date Title
CN102881281B (en) Noise cancellation system with lower rate emulation
KR101625361B1 (en) Active audio noise cancelling
DE60226003T2 (en) Control of return retraction in a telecommunications instrument
CN105122350B (en) Self-adapted noise elimination EFFECTIVENESS ESTIMATION and correction in personal audio set
US9330652B2 (en) Active noise cancellation using multiple reference microphone signals
CN101179873B (en) Noise canceling system and noise canceling method
JP6110936B2 (en) Coordinated control of adaptive noise cancellation (ANC) between ear speaker channels
EP3114825B1 (en) Frequency-dependent sidetone calibration
US20100131269A1 (en) Systems, methods, apparatus, and computer program products for enhanced active noise cancellation
US5696821A (en) Radiotelephone and method therefor for substantially reducing audio feedback
FI88570B (en) Telefonkrets som laemnar haenderna fria
US5657384A (en) Full duplex speakerphone
US6597787B1 (en) Echo cancellation device for cancelling echos in a transceiver unit
JP5420766B2 (en) System, method, apparatus and computer readable medium for adaptive active noise cancellation
CN104272381B (en) The downlink tone detection and adjustment of the secondary path response model in adaptive noise cancellation system
US20030152240A1 (en) Method and apperatus for communcation operator privacy
CN105284126B (en) The self-adapted noise elimination system and method for the dynamic bias of coefficient including self-adapted noise elimination system
JP5685311B2 (en) Active noise cancellation in portable audio devices.
CN104303228B (en) Error signal content is controlled in noise eliminates personal audio device secondary and the adjustment of leakage paths model
CN105074814B (en) Low time delay multiple driver self-adapted noise elimination (ANC) system of personal audio set
US20060229028A1 (en) Method and apparatus for providing a sidetone in a wireless communication device
US9230532B1 (en) Power management of adaptive noise cancellation (ANC) in a personal audio device
EP3081009B1 (en) Systems and methods for sharing secondary path information between audio channels in an adaptive noise cancellation system
CN104272378B (en) The noise burst adjustment of secondary path adaptive response in noise eliminates personal audio device
US8526628B1 (en) Low latency active noise cancellation system

Legal Events

Date Code Title Description
AS Assignment

Owner name: CIRRUS LOGIC, INC., TEXAS

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:KWATRA, NITIN;REEL/FRAME:028121/0873

Effective date: 20120424

STCF Information on status: patent grant

Free format text: PATENTED CASE

MAFP Maintenance fee payment

Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1551); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

Year of fee payment: 4